Rene Descartes and Computer Science

We use variables to represent unknown values in mathematical problems every day. Descartes, who lived during the 16th – 17th century came up with the idea to use the lower letters of the English alphabet as variables in equations (such as x, y, z) and the upper letters of the alphabet as constants (a, b, c).

Reference: http://en.wikipedia.org/wiki/Ren%C3%A9_Descartes