Kant goes down in the history of thought as a giant. Kant declared himself neither empiricist nor rationalist but achieved a synthesis of the two in his greatest work The Critique of Pure Reason (1781), which marked the end of the period of the Enlightenment and began a new period of philosophy, German idealism. Kant claimed that knowledge was impossible without accepting truths from both rationalist and empiricist schools of thought. He based his ethics on reason and said that moral duties could be deduced by all rational beings.