By Gregorio Leti (at Wikipedia), 1667, translated by W. Aglionby 1669. Full title: Il nipotismo di Roma: or The history of the Popes nephews from the time of Sixtus the IV to the death of the last Pope Alexaner the VII. In two parts. Written originally in Italian, in the year 1667, and Englished by W.A.
The work here mentioned is a bitter satire against the Court Rome, written in Italian, and attributed to Gregorio Leti. It was first printed in 1667, without the name or place of printer, but it is from the press of the Elzevirs. The book obtained by Pepys was probably the anonymous English translation, “Il Nipotismo di Roma: or the history of the Popes nephews from the time of Sixtus the IV. to the death the last Pope Alexander the VII. In two parts. Written originally Italian in the year 1667 and Englished by W. A. London, 1669” 8vo. From this work the word Nepotism is derived, and is applied to the bad practice of statesmen, when in power, providing lucrative places for their relations.
This text comes from a footnote on a diary entry in the 1893 edition edited by Henry B. Wheatley.
Il nipotismo di Roma, or, The history of the popes nephews from the time of Sixtus the IV to the death of the last Pope Alexander the VII in two parts / written originally in Italian in the year 1667 ; and Englished by W.A.
Leti, Gregorio, 1630-1701., Aglionby, William, d. 1705.
London: Printed for John Starkey ..., 1669.
Re "The Pope's Nephews" http://en.wikipedia.org/wiki/Cardinal-nephew
Chart showing the number of references in each month of the diary’s entries.