Nicole Oresme

Nicole Oresme was born in Normandy around 1320 and educated at the University of Paris, where he later became a master of theology and eventually bishop of Lisieux. He spent most of his life as a churchman and royal counsellor to Charles V of France, for whom he translated Aristotle's Ethics, Politics, and On the Heavens into Middle French — inventing new vocabulary as he went, and helping to turn French into a language capable of discussing science.

His scientific legacy rests on a single, extraordinary idea. In a treatise titled Tractatus de configurationibus qualitatum et motuum, written around 1350, he proposed that any quantity that varies — speed, temperature, intensity of any kind — could be represented as a geometric figure. A horizontal line stood for time or extension; a vertical line at each point stood for the value of the quantity at that moment; the area under the curve was the total effect. This is the graph, in the modern sense. Oresme was the first person to draw one.

Using this method he proved what is now called the Merton mean-speed theorem: a body undergoing uniform acceleration from rest covers the same distance in a given time as a body moving at the average of the initial and final speeds. The proof is a triangle whose area equals that of a rectangle of half the height — a geometric argument that anticipates, by nearly three hundred years, the integral of v(t) = at used to derive Galileo's s = ½at².

Oresme also argued — against Aristotle and most of his contemporaries — that the Earth's daily rotation was more plausible than a rotating heaven, offered a proto-relativity argument for why we cannot feel the motion, and discussed the possibility of other worlds. He pulled back from fully endorsing heliocentrism out of theological caution, but the reasoning was centuries ahead of its time.

He died in 1382 as bishop of Lisieux. His manuscripts sat largely unread until the nineteenth century, when historians of science rediscovered them and realised that a medieval French bishop had invented the Cartesian graph and glimpsed the mathematics of uniform acceleration before Galileo was born.