The Prince. Niccolò Machiavelli

"The Prince" (Italian: «Il Principe») is a 16th-century political treatise by the Italian diplomat and political theorist Niccolò Machiavelli. From correspondence a version appears to have been distributed in 1513, using a Latin title, «De Principatibus» («About Principalities»). However, the printed version was not published until 1532, five years after Machiavelli's death. This was done with the permission of the Medici pope Clement VII, but «long before then, in fact since the first appearance of the 'Prince' in manuscript, controversy had swirled about his writings».
Although it was written as if it were a traditional work in the «mirrors for princes» style, it is generally agreed that it was especially innovative. This is only partly because it was written in the vernacular Italian rather than Latin, a practice which had become increasingly popular since the publication of Dante's «Divine Comedy» and other works of Renaissance literature.
"The Prince" is sometimes claimed to be one of the first works of modern philosophy, especially modern political philosophy, in which the effective truth is taken to be more important than any abstract ideal. It was also in direct conflict with the dominant Catholic and scholastic doctrines of the time concerning how to consider politics and ethics.