This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book is the first volume of a two-volume study of Dante Alighieri and Guido Cavalcanti, whom Dante regarded, during his formative years as a poet and philosopher, as his mentor and best friend. It establishes the premises for the philosophical approach to reading Cavalcanti’s poetry. The book opens by surveying Cavalcanti’s reputation, in his own time and in the several decades following his death, as the exemplary figure of the heterodox intellectual, as a so-called atheist and Aristotelian materialist for whom the Christian afterlife is nothing more than a useful fiction. It is an exposition of philosophical views and vocabulary requisite for the interpretation of Cavalcanti’s project. The book provides information on the philosopher’s version of salvation in the afterlife, the Conjunction with the Active Intellect, as variously treated by the three most important classical Islamic rationalist philosophers, al-Farabi, Avicenna, and Averroes.