This revolutionary study presents new facts and an original theory about the source of the thought and literature which are termed `modern'.Using fifty-one new translations of sonnets from four languages spanning more than seven centuries, Oppenheimer argues that modern thought and literature were born with the invention of the sonnet in thirteenth-century Italy. In revealing the sonnet as the first lyric form since the fall of the Roman Empire meant not for music or performance but for silent reading, the book demonstrates that the sonnet was the first modern literary form deliberately intended to portray the self in conflict and to explore self-consciousness.Professor Oppenheimer traces the influences of the sonnet, as invented by Giacomo da Lentino, combining historical fact with the history of ideas and literary criticism. He illustrates, in bilingual format, the sonnet's growing appeal and variety during the centuries that followed, with translations from Italian, German, French, and Spanish and examples from more than thirty-five poets. Previous scholarship is also discussed and for the first time the source of the form is established in Platonic-Pythagorean mathematics.