Nicole Oresme and the Latitude of Forms

Nicole Oresme was born in northern France in 1323. As a young man he studied theology, philosophy, and logic in Paris. He was friends with King Charles the Fifth of France, and he eventually became a bishop.

Oresme translated books by Aristotle on ethics and astronomy into French. He also wrote commentaries on Aristotle's books, and wrote books of his own on topics such as astronomy and economics.

Like other medieval philosophers, Oresme was interested in measuring "forms". Forms were an idea of Aristotle's; they included qualities like the velocity of a moving object and the temperature at different places in a material. The medieval discussions of these concepts were very long and complicated. Oresme decided to simplify them by drawing a picture.

Oresme made a graph of velocity versus time for an object moving with constant acceleration, like a falling ball. He marked moments of time, which he called longitudes, along a horizontal line. For each moment he drew a bar or latitude whose length represented the object's velocity at that moment. Oresme's graph looked something like this:

Except for the fact that he drew bars instead of points, Oresme's picture was just like a modern graph of a line. He even noticed that his graph had constant slope. But Oresme didn't graph curves besides lines, and he didn't know enough algebra (lots of algebra hadn't been invented yet!) to graph an equation. Still, Oresme's book on "latitudes of forms" was fairly popular. People made many copies, and once the printing press was available, several editions were printed.