The book explores the philosophical thinking of Petrarch and Boccaccio in contrast to the writings of contemporary mendicants. Examining both Latin and vernacular works, it investigates how these humanists poetically express the temporal, subjective, and emotional quality of moral sensibility, in a way that shifts to the reader the weight of discerning the ethical message. The book centers its analysis on a series of paradoxes pondered by these humanists: the self that changes yet persists over time; the awareness of self-deception; the individual's validation of authority; and the ethics of pleasure. This study is valuable to those interested in Renaissance philosophy, literature, religion, and the history of ideas.