Although Georg Wilhelm Friedrich Hegel considered Science of Logic essential to his philosophy, it has received scant commentary compared with the other three books he published in his lifetime. This book rescues Science of Logic from obscurity, arguing that its neglect is responsible for contemporary philosophy’s fracture into many different and opposed schools of thought. Through careful analysis, the book sheds new light on the precise problems that animate Hegel’s overlooked book and their tremendous significance to philosophical conceptions of logic and reason. The book’s overarching question is how, if at all, rationalism can overcome the split between monism and dualism. Monism—which claims a singular essence for all things—ultimately leads to nihilism, while dualism, which claims multiple, irreducible essences, leads to what the book calls “the endless chatter of the history of philosophy.” Science of Logic, the book argues, is the fundamental text to offer a new conception of rationalism that might overcome this philosophical split. Leading readers through Hegel’s book from beginning to end, the book’s argument culminates in a masterful chapter on the Idea in Hegel.