Usually Leibniz (1646–1716) is regarded as a great rival of Newton. That is true, with respect to the achievements of these two thinkers in the field of mathematics (the creation of the differential and integral calculus) and certain positions in the philosophy of nature. But in the most important matters, concerning the foundations of philosophical thought, Leibniz most often attacked not Newton, but Descartes. Nothing is more foreign to Leibniz than a "geometrical mechanism" which reduces the essence of bodies to their extension and reduces all of their activity to purely mechanical contact like friction and impact. Leibniz" dislike of Descartes' style of thought has its foundation, however, in a certain similarity between the two philosophers.