The magic of early Renaissance architecture. The notion that numerical proportional systems contribute to the serene, orderly appearance of the basilica of San Lorenzo has long stood as a virtual axiom of architectural history. In this book, Cohen challenges this and many other long-standing preconceptions about proportional systems in the history of architecture. Using Brunelleschi's basilicas of San Lorenzo and Santo Spirito as case studies, the author presents a detailed analysis of his comprehensive measurements of these buildings, which he recorded from scaffolding, meticulous observations of the built fabric, and a variety of documentary sources. This book presents a rigorous new approach to an important but little studied area of architectural history and is essential reading for anyone interested in medieval and Renaissance architecture.