Published here in the original German and French, along with an English translation, the correspondence between Albert Einstein and Elie Cartan includes letters written between 1929 and 1932, after which time Einstein abandoned his unified field theory based on absolute parallelism. Originally published in 1979. 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.