November 11, 1675 – Leibniz demonstrates integral calculus for the first time to find the area under the graph of the Y = F(X) function. Gottfried Wilhelm (von) Leibniz was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is a prominent figure in both the history of philosophy and the history of mathematics. He wrote works on philosophy, theology, ethics, politics, law, history and philology.