In analyzing the factors that have improved health and enhanced longevity during the last three centuries, Thomas McKeown contends that nutritional, environmental, and behavioral changes have been and will be more important than specific medical measures, especially clinical or curative measures. Originally published in 1980. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.