Erasmus or Erasmus of Rotterdam (1466-1536), was a Dutch Renaissance humanist, Catholic priest, social critic, and theologian. He was a leader of the then-dawning Age of Enlightenment. His books were in two fields: theology and practical living, what we call self-help books today. In the 1530s, his books constituted 20 % of all the books sold in Europe. His books take up ten columns of the catalog of the British Library.