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Order of Friars Minor
Statue of Roger Bacon
in the Oxford University Museum
|Died||1292 (aged c. 78)
|Other names||Doctor Mirabilis|
|Organization||Order of Friars Minor|
Roger Bacon, OFM (/ˈbeɪkən/; c. 1214 – June 1292?; scholastic accolade Doctor Mirabilis, meaning "wonderful teacher"), was an English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empirical methods. He is sometimes credited (mainly since the nineteenth century) as one of the earliest European advocates of the modern scientific method inspired by Aristotle and later Arabic scholars such as the Muslim scientist Alhazen. However, more recent re-evaluations emphasise that he was essentially a medieval thinker, with much of his "experimental" knowledge obtained from books, in the scholastic tradition. A survey of how Bacon's work was received over the centuries found that it often reflected the concerns and controversies that were central to his readers.
Roger Bacon was born in Ilchester in Somerset, England, possibly in 1213 or 1214 at the Ilchester Friary. The only source for his birth date is his statement in the Opus Tertium, written in 1267, that "forty years have passed since I first learned the alphabet". The 1214 birth date assumes he meant exactly 40 years had passed since he matriculated at Oxford at age 13. If he had been literal, it is more likely he was born around 1220 to 1222, but the figure forty was also widely used in the Middle Ages simply as a synonym for many, leaving his actual date of birth in doubt. In the same passage he said that for all but two of the forty years he had been engaged in study. His family appears to have been well-off, but during the stormy reign of Henry III of England their property was seized and several family members driven into exile.
Bacon studied at Oxford and may have been a disciple of Grosseteste. He became a master at Oxford, lecturing on Aristotle. There is no evidence he was ever awarded a doctorate—the title Doctor Mirabilis was posthumous and figurative. Sometime between 1237 and 1245, he began lecturing at the University of Paris, then the centre of European intellectual life. Where he was between 1247 and 1256 is unknown, but about 1256 he became a friar in the Franciscan Order, and no longer held a teaching post. After 1260, his activities were restricted by a Franciscan statute prohibiting friars from publishing books or pamphlets without prior approval.
Bacon circumvented this through his acquaintance with Cardinal Guy le Gros de Foulques, who became Pope Clement IV in 1265. Clement IV issued a mandate ordering Bacon to write to him concerning the place of philosophy within theology. Bacon sent the Pope his Opus Majus, which presented his views on how to incorporate the philosophy of Aristotle and science into a new Theology. Bacon also sent his Opus minus, De multiplicatione specierum, and possibly other works on alchemy and astrology.
Pope Clement died in 1268 and Bacon lost his protector. Some time between 1277 and 1279, Bacon was apparently imprisoned or placed under house arrest for his excessive credulity in alchemy and for his harsh regard for the other innovators of his time. Some time after 1278 Bacon returned to the Franciscan House at Oxford, where he continued his studies and is presumed to have spent most of the rest of his life. He is said to have died in June of 1292 (the year of his last dateable writing, Compendium studii theologiae) and to be buried in Oxford.
Changing interpretations of Roger Bacon
In the early modern period, Bacon gained a reputation as the epitome of a wise and subtle possessor of forbidden knowledge, a Faust-like magician who had tricked the devil and so was able to go to heaven. Of these legends, one of the most prominent was that he created a brazen talking head which could answer any question. The most famous account of Bacon from this point of view is Robert Greene's late sixteenth-century Friar Bacon and Friar Bungay.
In the nineteenth century it was a widely held interpretation that Bacon was a modern experimental scientist who had emerged before his time. This reflected two prevalent views of the period: an emphasis upon experiment as the principal form of scientific activity and a general acceptance of the characterisation of the Middle Ages as the "Dark Ages". Some writers of the period carried this account further.In this view, which is still reflected in some 21st-century popular science books, Bacon would be an advocate of modern experimental science who somehow emerged as an isolated figure in an age supposed to be hostile toward scientific ideas. He was also presented as a visionary; for instance, Frederick Mayer wrote that Bacon predicted the invention of the submarine, automobile, and aircraft.
However, in the course of the 20th century, the philosophical understanding of the role of experiment in the sciences was substantially modified. Starting with works of Pierre Duhem, Raoul Carton, and Lynn Thorndike, it is argued that Bacon's advocacy of scientia experimentalis differed from modern experimental science. New historical research has also shown that medieval Christians were not generally opposed to scientific investigation and has revealed the extent and variety of medieval science. In fact, many medieval sources of, and influences on, Bacon's scientific activity have been identified. For instance, Bacon's idea that inductively derived conclusions should be submitted for further experimental testing is very much like Robert Grosseteste's 'Method of Verification', and Bacon's work on optics and the calendar also followed the lines of inquiry of Grosseteste.
As a result, the picture of Bacon has changed. One recent study summarised that: "Bacon was not a modern, out of step with his age, or a harbinger of things to come, but a brilliant, combative, and somewhat eccentric schoolman of the thirteenth century, endeavoring to take advantage of the new learning just becoming available while remaining true to traditional notions... of the importance to be attached to philosophical knowledge". Thus, rather than being isolated, Bacon is now seen as a leading figure in the beginnings of medieval universities at Paris and Oxford, among other contemporary exponents of this shift in the philosophy of science (as we call it today), including Grosseteste (who preceded Bacon), William of Auvergne, Henry of Ghent, Albert Magnus, Thomas Aquinas, John Duns Scotus, and William of Ockham.
As to the alleged persecution, the first known reference to an imprisonment originates around eighty years after Bacon's death. It says the order was given by the head of the Franciscans because of unspecified "suspected novelties". However, the fact that no earlier report has been found drives scepticism over the assertion. Moreover, current historians of science who see an incarceration as plausible typically do not connect it with Bacon's scientific writings. Instead, if it happened, scholars speculate that his troubles resulted from such things as his sympathies for radical Franciscans, attraction to contemporary prophecies, or interest in certain astrological doctrines. Bacon's personality has also been mentioned as a factor.
A recent review of the many visions that each age has held about Roger Bacon says contemporary scholarship still neglects one of the most important aspects of his life and thought: the commitment to the Franciscan order. "His Opus maius was a plea for reform addressed to the supreme spiritual head of the Christian faith, written against a background of apocalyptic expectation and informed by the driving concerns of the friars. It was designed to improve training for missionaries and to provide new skills to be employed in the defence of the Christian world against the enmity of non-Christians and of the Antichrist. It cannot usefully be read solely in the context of the history of science and philosophy."
View of the past
Bacon contrasts Aristotle's argument that facts be collected before deducing scientific truths with a description of his perception of his contemporaries. Bacon argues that physical science in his time is not carried out by observations from the natural world, but by arguments based solely on tradition and prescribed authorities.
The mathematicians whom Bacon considers perfect are Peter of Maricourt and John of London, and two he considers good: Campanus of Novara and a Master Nicholas. Peter was the author of a famous letter to a friend, Epistola de Magnete, in which he describes some of the earliest European experiments with magnetism. Campanus wrote several important works on astronomy, astrology, and the calendar. Bacon often mentioned his debt to the work of Robert Grosseteste and Adam Marsh, as well as to other lesser figures. He was clearly not an isolated scholar in the thirteenth century.
In his writings, Bacon calls for a reform of theological study. Less emphasis should be placed on minor philosophical distinctions than had been the case in scholasticism. Instead, the Bible itself should return to the centre of attention and theologians should thoroughly study the languages in which their original sources were composed. He was fluent in several languages and lamented the corruption of the holy texts and the works of the Greek philosophers by numerous mistranslations and misinterpretations. Furthermore, he urged all theologians to study all sciences closely, and to add them to the normal university curriculum. With regard to the obtaining of knowledge, he strongly championed experimental study over reliance on authority, arguing that "thence cometh quiet to the mind". Bacon did not restrict this approach to theological studies. He rejected the blind following of prior authorities, both in theological and scientific study, which was the accepted method of undertaking study in his day.
In the Opus Minus he criticises his contemporaries Alexander of Hales and Albertus Magnus, who, he says, had not studied Aristotelian texts but only acquired their learning during their life as preachers. Albert was received at Paris as an authority equal to Aristotle, Avicenna, and Averroes, leading Bacon to proclaim that "never in the world [had] such monstrosity occurred before."
The study of optics in part five of Opus Majus draws heavily on the works of both Claudius Ptolemy (his Optics in Arabic translation) and the Islamic scientists Alkindus (al-Kindi) and Alhazen (Ibn al-Haytham). He includes a discussion of the physiology of eyesight, the anatomy of the eye and the brain, and considers light, distance, position, and size, direct vision, reflected vision, and refraction, mirrors and lenses. His research in optics was primarily oriented by the legacy of Alhazen through a Latin translation of the latter's monumental Kitab al-manazir (De aspectibus; Perspectivae; The Optics), while the impact of the tradition of al-Kindi (Alkindus) was principally mediated through the influence that this Muslim scholar had on the optics of Robert Grosseteste. Moreover, Bacon's investigations of the properties of the magnifying glass partly rested on the handed-down legacy of Islamic opticians, mainly Alhazen, who was in his turn influenced by Ibn Sahl's 10th-century legacy in dioptrics.
He was a forerunner in Calendar reformation. Drawing on the recently discovered Greco-Muslim astronomy and on the calendaric writings of Robert Grosseteste, Bacon criticised the Julian calendar, describing it as intolerable, horrible and laughable.
He had correctly deduced that the assumption of Julius Caesar's year of length of 365 days and a quarter was wrong. He proposed to Pope Clement IV in 1267 in his Opus Majus (Part IV) to rectify these errors by dropping a day every 125 years. By not doing this correction, a surplus of time over the centuries had accumulated to nine days during his time. He charged that the then current notion of fixed equinoxes and solstices was also wrong. As this is important in calculating the date of Easter, he was extremely distressed that Christians were celebrating Easter and other holy festivals on the wrong dates, because of this error. Unfortunately, the untimely death of Pope Clement IV in 1268 put an end to his hopes.
Other attributed works
In his own writings of 1260–1280 Bacon cited Secretum secretorum, which he attributed to Aristotle, far more than his contemporaries did. Often used as an argument for the special influence that this work had on Bacon's own is the manuscript of Secretum that Bacon edited, complete with his own introduction and notes, something Bacon seldom did with others' works. Although some early 20th century scholars like Robert Steele have pushed further along this path, arguing that Bacon's contact with the Secretum was a turning point in Bacon's philosophy, transforming him into an experimentalist, there is no clear reference to such a decisive impact of the Secretum in Bacon's own words. The dating of Bacon's edition of the Secretum is a key argument in this debate, but is still unresolved, with those arguing for a greater impact dating it earlier than those who urge caution in this interpretation.
The cryptic Voynich manuscript has been attributed to Bacon by various sources, including by its first recorded owner, in a book drafted by William Romaine Newbold and posthumously edited and published by Roland Grubb Kent in 1928, and in a 2005 book of Lawrence and Nancy Goldstone published by Doubleday and Broadway Books. In strongly worded terms, historians of science Lynn Thorndike and George Sarton have dismissed these claims as unsupported. (The vellum of the Manuscript has since been dated to the first part of the 15th century.)
Another work of contentious date and even origin is the Epistola de Secretis Operibus Artis et Naturae, et de Nullitate Magiae (meaning Letter on the Secret Workings of Art and Nature, and on the Vanity of Magic), sometimes alternatively entitled De Mirabili Potestate Artis et Naturae (On the Wonderful Powers of Art and Nature). This treatise dismisses magical practices like necromancy, and contains most of the alchemical work attributed to Bacon, chiefly a formula for philosopher's stone, and perhaps one for gunpowder. It also contains a number of passages about hypothetical flying machines and (what we today call) submarines, attributing their first use to Alexander the Great.
Bacon is also the ascribed author of the alchemical manual Speculum Alchemiae, which was translated into English as The Mirror of Alchimy in 1597. It is a short treatise about the composition and origin of metals, espousing "conventional" (with respect to the period) Arabian theories of mercury and sulphur as the constituents of metals, and containing vague allusions to transmutation. About this work, John Maxson Stillman wrote that "there is nothing in it that is characteristic of Roger Bacon's style or ideas, nor that distinguishes it from many unimportant alchemical lucubrations of anonymous writers of the thirteenth to the sixteenth centuries". M. M. Pattison Muir had a similar opinion, and Edmund Oscar von Lippmann considered this text a pseudepigraph.
Bacon is often considered the first European to describe a mixture containing the essential ingredients of gunpowder. Based on two passages from Bacon's Opus Majus and Opus Tertium, extensively analysed by J. R. Partington, several scholars cited by Joseph Needham concluded that Bacon had most likely witnessed at least one demonstration of Chinese firecrackers, possibly obtained with the intermediation of other Franciscans, like his friend William of Rubruck, who had visited the Mongols. The most telling passage reads: "We have an example of these things (that act on the senses) in [the sound and fire of] that children's toy which is made in many [diverse] parts of the world; i.e. a device no bigger than one's thumb. From the violence of that salt called saltpetre [together with sulphur and willow charcoal, combined into a powder] so horrible a sound is made by the bursting of a thing so small, no more than a bit of parchment [containing it], that we find [the ear assaulted by a noise] exceeding the roar of strong thunder, and a flash brighter than the most brilliant lightning."
More controversial are the claims originating with Royal Artillery colonel Henry William Lovett Hime (at the beginning of the 20th century) that a cryptogram existed in Bacon's Epistola, giving the ratio of ingredients of the mixture. These were published, among other places, in the 1911 edition of Encyclopædia Britannica. An early critic of this claim was Lynn Thorndike, starting with a letter in the 1915 edition of the journal Science, and repeated in several books of his. M. M. Pattison Muir also expressed his doubts on Hime's theory, and they were echoed by John Maxson Stillman. Robert Steele and George Sarton also joined the critics. Needham concurred with these earlier critics in their opinion that the additional passage does not originate with Bacon. In any case, the proportions claimed to have been deciphered (7:5:5 saltpetre:charcoal:sulfur) are not even useful for stuffing firecrackers, burning slowly while producing mostly smoke, and failing to ignite inside a gun barrel. The ~41% nitrate content is too low to have explosive properties.
In twentieth-century fiction
To commemorate Bacon's seven hundredth anniversary, Professor John Erskine wrote A Pageant of the Thirteenth Century, a biographical play which was produced at Columbia University and published as a book by Columbia University Press in 1914.
An accessible description of Roger Bacon's life and times is contained in the fiction book Doctor Mirabilis, written in 1964 by the science fiction author James Blish. This is the second book in Blish's quasi-religious trilogy After Such Knowledge, and is a recounting of Bacon's life and struggle to develop a 'Universal Science'. Though thoroughly researched, with a host of references, including extensive use of Bacon's own writings, frequently in the original Latin, the book is written in the style of a novel, and Blish himself referred to it as 'fiction' or 'a vision'. Blish's view of Bacon is uncompromisingly that he was the first scientist, and he provides a postscript to the novel in which he sets forth these views. Central to his depiction of Roger Bacon is that 'He was not an inventor, an Edison or Luther Burbank, holding up a test tube with a shout of Eureka!' He was instead a theoretical scientist probing fundamental realities, and his visions of modern technology were just by-products of "...the way he normally thought – the theory of theories as tools..." Blish indicates where Bacon's writings, for example, consider Newtonian metrical frameworks for space, then reject these for something which reads remarkably like Einsteinian Relativity, and all '...breathtakingly without pause or hiccup, breezily moving without any recourse through over 800 years of physics'.
In John Bellairs' The Face in the Frost, Roger Bacon is friend of the main character.
Bacon also appears as first scientist in The Black Rose, the most commercially successful book by Thomas Costain, written in 1945. The Black Rose is set in the Middle Ages. Bacon's personal presence in the narrative is brief, but includes a demonstration of gunpowder and a few sentences outlining a philosophy of science which might as easily be attributed to Francis Bacon centuries later. The novel's Roger Bacon serves to motivate Costain's protagonist, a fictional Englishman who journeys to China during the reigns of Edward I and Kublai Khan. Costain's narration includes technology such as the compass, the telescope, rockets and the manufacture of paper, all described by his young adventurer with an eye toward bringing these marvels back to Bacon for analysis. Returning to England to find Bacon gone and under house arrest, the traveller begs King Edward to intercede with the pope for the Franciscan's release, arguing that with Bacon's imprisonment a great light of the world is in danger of being put out. Costain's character also comes to argue for emancipation of the Saxon villeins (serfs), linking political with intellectual enlightenment under the fictional Bacon's influence.
In the novel The Name of the Rose by Umberto Eco, the story follows the investigations of William of Baskerville, presented as an anachronistically empiricist contemporary and colleague of Roger Bacon who often quotes his late friend when explaining William's own methods.
Roger Bacon is a supporting character in the video game series Shadow Hearts. He is portrayed as an immortal magician and scientist who is over 700 years old. Bacon is also mentioned briefly in Ubisoft's Assassin's Creed IV: Black Flag, in a readable document found by the player when hacking into various computer systems within the game's modern day setting.
- Roger Bacon High School
- Oxford Franciscan school
- History of geomagnetism
- History of the scientific method
- History of science in the Middle Ages
- List of Roman Catholic scientist-clerics
- Baco (crater) on the Moon
- Linda S. Noelker, Kenneth Rockwood, Richard Sprott (ed.), The Encyclopedia of Aging: A-K, Springer Publishing Company, 2006, p. 69.
- James S. Ackerman (1978). "Leonardo's Eye" 41. Journal of the Warburg and Courtauld Institutes. p. 119.
- Glick, Thomas F.; Livesey, Steven John; Wallis, Faith: Medieval Science, Technology, and Medicine: An Encyclopedia, first edition, Routledge, 29 September 2005, ISBN 978-0-415-96930-7, p. 71
- Power, A. (2006). "A Mirror for Every Age: The Reputation of Roger Bacon". The English Historical Review 121 (492): 657–692. doi:10.1093/ehr/cel102. Retrieved 12 July 2007.
- James, R. R. (1928). "The Father of British Optics: Roger Bacon, c. 1214–1294". British Journal of Ophthalmology 12 (1): 1–14. doi:10.1136/bjo.12.1.1. PMC 511940. PMID 18168687.
- Jeremiah Hackett, "Roger Bacon: His Life, Career, and Works," in Hackett, Roger Bacon and the Sciences, pp. 9–11.
- Jeremiah Hackett, "Roger Bacon: His Life, Career, and Works," in Hackett, Roger Bacon and the Sciences, pp. 13–17.
- Jeremiah Hackett, "Roger Bacon: His Life, Career, and Works," in Hackett, Roger Bacon and the Sciences, pp. 17–19.
- Jeremiah Hackett, "Roger Bacon: His Life, Career, and Works," in Hackett, Roger Bacon and the Sciences, pp. 19–20.
- Molland, George (2004). "Bacon, Roger (c.1214–1292?)". Oxford Dictionary of National Biography (Online ed.). Oxford University Press. doi:10.1093/ref:odnb/1008. Retrieved 2014-11-20. (subscription or UK public library membership required)
- John Fauvel; Raymond Flood; Robin J. Wilson (2000). Oxford figures: 800 years of the mathematical sciences. Oxford University Press. p. 2. ISBN 978-0-19-852309-3.
- Allison Kavey, Books of Secrets: Natural Philosophy in England, 1550–1600 (2007), pp. 38–39; another key text promoting this image was The Famous Historie of Fryer Bacon, containing the wonderfull things that he did in his life also the manner of his death; With the lives and deaths of the two conjurers, Bungye and Vandermast. Very pleasant and delightfull to be read. Printed in London by E. A. for Francis Groue, and are to be sold at his shop, at the upper-end of Snow-hill, against the Sarazens head. 1630. Ed. by William J. Thoms, Early English prose romances: with bibliographical and historical introductions, 2nd edn, 3 vols (London: Nattali and Bond, 1858).
- William Whewell, History of the Inductive Sciences from the Earliest Times to the Present Times, vol. 1, New York, 1859, p. 245; cited in Jeremiah Hackett, Roger Bacon and the Sciences, p. 279
- Charles Sanders Peirce (1877). "The Fixation of Belief".
To Roger Bacon, that remarkable mind who in the middle of the thirteenth century was almost a scientific man, the schoolmen's conception of reasoning appeared only an obstacle to truth. He saw that experience alone teaches anything.... Of all kinds of experience, the best, he thought, was interior illumination, which teaches many things about Nature which the external senses could never discover, such as the transubstantiation of bread.
- Clegg, Brian (2003). The First Scientist: A Life of Roger Bacon. Constable & Robinson. ISBN 0-7867-1358-5. ; see also review of this book by Benjamin Woolley (17 May 2003) The Magus. Brian Clegg presents Roger Bacon as a great intellectual in his biography of the medieval innovator, The First Scientist. But can he live up to his title? Benjamin Woolley isn't convinced, The Guardian
- Lawrence Goldstone and Nancy Goldstone (2006). The Friar and the Cipher: Roger Bacon and the Unsolved Mystery of the Most Unusual Manuscript in the World. Broadway Books. ISBN 0-7679-1472-4.
- Douglas Gray (2011). From the Norman Conquest to the Black Death: An Anthology of Writings from England. Oxford University Press. p. 184. ISBN 978-0-19-812353-8.
- Frederick Mayer. A History of Educational Thought. 2nd edition, Columbus, Ohio: Charles E. Merrill Books, Inc, 1966, pp 500–501.
- Jeremiah Hackett, Roger Bacon and the Sciences, p. 280
- David C. Lindberg, Roger Bacon and the Origins of Perspectiva in the Middle Ages: A Critical Edition and English Translation of Bacon's Perspectiva with Introduction and Notes, Oxford: Oxford University Press, 1996, p. lv ISBN 0-19-823992-0
- David C. Lindberg, "The Medieval Church Encounters the Classical Tradition: Saint Augustine, Roger Bacon, and the Handmaiden Metaphor", in David C. Lindberg and Ronald L. Numbers, ed. When Science & Christianity Meet, (Chicago: University of Chicago Pr., 2003).
- Quotation: "If revolutionary rational thoughts were expressed in the Age of Reason [the 18th century], they were only made possible because of the long medieval tradition that established the use of reason as one of the most important of human activities". (p. 9) In: Edward Grant: God and Reason in the Middle Ages, Cambridge 2001.
- Jeremiah Hackett, "Roger Bacon on Scientia Experimentalis," in Hackett, Roger Bacon and the Sciences, pp. 279–84
- Hugh G. Gauch (2003). Scientific method in practice. Cambridge University Press. p. 222. ISBN 978-0-521-01708-4.
- Alistair Cameron Crombie (1990). Science, optics, and music in medieval and early modern thought. Continuum International Publishing Group. p. 129. ISBN 978-0-907628-79-8.
- Lindberg, "Science as Handmaiden," p. 520
- Hugh G. Gauch (2003). Scientific method in practice. Cambridge University Press. p. 51. ISBN 978-0-521-01708-4.
- The late-14th century Chronicle of the Twenty-Four Generals reports an imprisonment, as mentioned in: Roger Bacon, Thomas S. Maloney, "Compendium of the study of theology", p. 8
- Quotation: "The assertion that Bacon was imprisoned (allegedly by the head of his own Franciscan order) ﬁrst originates some eighty years after his death and has drawn skepticism on these grounds alone. Scholars who ﬁnd this assertion plausible connect it with Bacon's attraction to contemporary prophecies that have nothing to do with Bacon's scientiﬁc, mathematical, or philosophical writings." (p.21). Chapter 2, by Michael H. Shank in Ronald L. Numbers (ed.) Galileo Goes to Jail, and Other Myths about Science and Religion (Cambridge, MA: Harvard University Press, 2009).
- Lindberg, D.C. (1995). "Medieval Science and Its Religious Context". Osiris 10 (10): 60–79. doi:10.1086/368743. JSTOR 301913.
his imprisonment, if it occurred at all (which I doubt) probably resulted from his sympathies for the radical 'poverty' wing of the Franciscans (a wholly theological matter) rather than from any scientific novelties which he may have proposed (p. 70)
- Sidelko, Paul L. (March 1996). "The condemnation of Roger Bacon". Journal of Medieval History 22 (1): 69–81. doi:10.1016/0304-4181(96)00009-7.
- Roger Bacon, Thomas S. Maloney, "Compendium of the study of theology", p. 8
- Turner, Gillian (2010). North Pole, South Pole : the epic quest to solve the great mystery of Earth's magnetism (1st North American ed.). New York, NY: The Experiment, LLC. ISBN 978-1-61519-031-7.
- Molland, George (1997). "Roger Bacons Knowledge of Mathematics". In Hackett, Jeremiah. Roger Bacon and the sciences: commemorative essays. pp. 151–174. ISBN 978-90-04-10015-2.
- Jeremiah Hackett, "Roger Bacon: His Life, Career, and Works," in Hackett, Roger Bacon and the Sciences, pp. 11–12.
- Jeremiah Hackett, "Roger Bacon on the Classification of the Sciences," in Hackett, Bacon and the Sciences, pp. 49, 51–2
- Hackett, Jeremiah M. G. (1980), "The Attitude of Roger Bacon to the Scientia of Albertus Magnus", in Weisheipl, James A., Albertus Magnus and the Sciences: Commemorative Essays, Studies and texts 49, Toronto: Pontifical Institute of Mediaeval Studies, pp. 53–72, ISBN 0-88844-049-9
- Stewart C. Easton, Roger Bacon and his Search for a Universal Science, New York: Columbia Univ. Pr., 1952, pp. 210–219
- Richard LeMay, Roger Bacon's Attitude toward the Latin Translations and Translators of the Twelfth and Thirteenth Centuries, in Hackett, Bacon and the Sciences, pp. 40–41
- A. Mark Smith (1996). Ptolemy's theory of visual perception: an English translation of the Optics. American Philosophical Society. p. 58. ISBN 978-0-87169-862-9.
- Nader El-Bizri, "A Philosophical Perspective on Alhazen's Optics", Arabic Sciences and Philosophy, Vol. 15, Issue 2 (2005), pp. 189–218 (Cambridge university Press)
- Opus Majus, Volume I, Part IV, ed. by John Henry Bridges, 1900.
- John D. North, "The Western Calendar: – 'Intolerabilis, Horribilis, et Derisibilis'; Four Centuries of Discontent", pp. 75–113 in: G. V. Coyne, M. A. Hoskin, and O. Pedersen (ed.), Gregorian Reform of the Calendar: Proceedings of the Vatican conference to commemorate its 400th anniversary (Citta del Vaticano: Specola Vaticana, 1983), pp. 75, 82–4.
- David Ewing Duncan, The Calendar, 2011, pp. 1–2.
- Steven J. Williams (1997). "Roger Bacon and the Secret of Secrets". In Jeremiah Hackett. Roger Bacon and the sciences: commemorative essays. BRILL. pp. 365–374. ISBN 978-90-04-10015-2.
- William Romaine Newbold; Roland Grubb Kent (2003) . Cipher of Roger Bacon. Kessinger Publishing. ISBN 978-0-7661-7956-1.
- Margaret Farley Steele (20 February 2005). "The Bacon Code". New York Times.
- Lynn Thorndike (January 1929). "The Opus Majus of Roger Bacon by Robert Belle Burke. The Cipher of Roger Bacon by William Romaine Newbold; Roland Grubb Kent". The American Historical Review 34 (2): 317–319. JSTOR 1838571.
- George Sarton (September 1928). "The Cipher of Roger Bacon by William Romaine Newbold; Roland Grubb Kent". Isis 11 (1): 141–145. doi:10.1086/346365. JSTOR 224770.
- Benjamin R. Foster (1999). "Newbold, William Romaine". In John Arthur Garraty, Mark Christopher Carnes. American National Biography: Mosler-Parish. Oxford University Press. p. 326. ISBN 978-0-19-512795-9.
- Joseph Needham; Gwei-Djen Lu; Ling Wang (1987). Science and civilisation in China, Volume 5, Part 7. Cambridge University Press. pp. 48–50. ISBN 978-0-521-30358-3.
- Robert Bartlett (2008). The natural and the supernatural in the Middle Ages: the Wiles lecture given at the Queen's University of Belfast, 2006. Cambridge University Press. p. 124. ISBN 978-0-521-70255-3.
- Paola Zambelli (2007). White magic, Black magic in the European Renaissance. BRILL. pp. 48–49. ISBN 978-90-04-16098-9.
- William R. Newman (1997). "An overview of Roger Bacon's Alchemy". In Jeremiah Hackett. Roger Bacon and the sciences: commemorative essays. BRILL. pp. 328–329. ISBN 978-90-04-10015-2.
- Douglas Gray (2011). From the Norman Conquest to the Black Death: An Anthology of Writings from England. Oxford University Press. pp. 185–186. ISBN 978-0-19-812353-8.
- Hub Zwart (2008). Understanding Nature: Case Studies in Comparative Epistemology. Springer. p. 236. ISBN 978-1-4020-6491-3.
- John Maxson Stillman (2003) . Story of Alchemy and Early Chemistry. Kessinger Publishing. p. 271. ISBN 978-0-7661-3230-6.
- Arnold Pacey (1991). Technology in world civilization: a thousand-year history (reprint, illustrated ed.). MIT Press. p. 45. ISBN 0-262-66072-5. Retrieved 28 November 2011.
Europeans were prompted by all this to take a closer interest in happenings far to the east. Four years after the invasion of 1241, the pope sent an ambassador to the Great Khan's capital in Mongolia. Other travellers followed later, of whom the most interesting was William of Rubruck (or Ruysbroek). He returned in 1257, and in the following year there are reports of experiments with gunpowder and rockets at Cologne. Then a friend of William of Rubruck, Roger Bacon, gave the first account of gunpowder and its use in fireworks to be written in Europe. A form of gunpowder had been known in China since before AD 900, and as mentioned earlier...Much of this knowledge had reached the Islamic countries by then, and the saltpetre used in making gunpowder there was sometimes referred to, significantly, as 'Chinese snow'.CS1 maint: Extra text (link)
- William Richard Eaton Hodgkinson (1911). " Gunpowder". In Chisholm, Hugh. Encyclopædia Britannica (Eleventh ed.). Cambridge University Press. Wikisource.
- Thorndike, L. (1915). "Roger Bacon and Gunpowder". Science 42 (1092): 799. Bibcode:1915Sci....42..799T. doi:10.1126/science.42.1092.799-a.
- John Maxson Stillman (2003) . Story of Alchemy and Early Chemistry. Kessinger Publishing. p. 202. ISBN 978-0-7661-3230-6.
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- Roger Bacon entry by Jeremiah Hackett in the Stanford Encyclopedia of Philosophy
- Roger Bacon entry in the Internet Encyclopedia of Philosophy
- Roger Bacon on Language entry in the Internet Encyclopedia of Philosophy
- "Roger Bacon" in the 1913 Catholic Encyclopedia.
- 1901–1906 Jewish Encyclopedia: Bacon, Roger
- Roger Bacon Quotes at Convergence
- Fr. Rogeri Bacon Opera quaedam hactenus Inedita. Vol. I at Google Books. Contains the Opus Tertium, Opus Minus, and Compendium Philosophiae. Edited by John Sherren Brewer (1859).
- Roger Bacon: On Experimental Science, 1268
- O'Connor, John J.; Robertson, Edmund F., "Roger Bacon", MacTutor History of Mathematics archive, University of St Andrews .
- Brehm, Edmund A., ″Roger Bacon's Place in the History of Alchemy″