This book is the first intellectual biography of Colin Maclaurin to appear in English. It traces the development of his mathematical thought through three major phases of his career: an early period shaped primarily by geometry, a second period centered on algebraic methods, and a final period of synthesis in which he engaged deeply with Newton's method of fluxions and fluents. Maclaurin's scientific work was closely intertwined with the social and intellectual life of eighteenth-century Scotland and Great Britain. Through both his mathematical achievements and his extensive network of personal and scholarly connections, he actively promoted a practical and dynamic form of Newtonianism closely linked to the advancement of his country. At the same time, Maclaurin was far more than a mere follower of Newton. This book shows how he emerged as one of the most important interpreters and defenders of Newtonian science while also transforming and extending it. The book will appeal both to readers interested in the intellectual and cultural history of science and to those curious about the mathematics itself. While the historical and biographical discussions are accessible to any interested reader, the mathematical passages can be appreciated with no more than a high-school background in mathematics.