Dürer took many prints with him. He wrote in his diary to whom he gave, exchanged, or sold them, and for how much. This is some of the few times the price of prints was recorded, so historians think it very important to show the values of prints compared to paintings at that time. Dürer returned home in July 1521. He had an unknown illness which stayed with him for the rest of his life, and slowed his rate of work.