Durer always lived in a frugal manner, without the least ostentation for the distinguished favors heaped upon him. He applied himself to his profession with the most constant and untiring industry, which, together with his great knowledge, great facility of mechanical execution, and a remarkable talent for imitation, enabled him to rise to such distinction, and to exert so powerful an influence on German art for a great length of time. He was the first artist in Germany who practiced and taught the rules of perspective, and of the proportions of the human figure, according to mathematical principles. His treatise on proportions is said to have resulted from his studies of his picture of Adam and Eve. His principal works are De Symmetria partium in rectis formis humanorum corporum, printed at Nuremberg in 1532; and De Verieitate Figurarum, et flexuris partium, et Gestibus Imaginum; 1534. These works were written in German, and after Durer's death translated into Latin. The figures illustrating the subjects were executed by Durer, on wood, in an admirable manner. Durer had also much merit as a miscellaneous writer, and labored to purify and elevate the German language, in which he was assisted by his friend, W. Pirkheimer. His works were published in a collected form at Arnheim, in 1603, folio, in Latin and in French. J. J. Roth wrote a life of Durer, published at Leipsic in 1791.