Before Boole there were others: Euclid, Euler, Newton and the Bernoullis.

FORBES: The Original Hacker and Why His Work, 300 Years Ago, Matters Today

And, as Euler's successor, Carl Friedrich Gauss, was to discover, if you plot real numbers on one axis of a graph and imaginary ones on the other, you create a plane that represents both sorts of numbers.

ECONOMIST: Beno?t Mandelbrot

Mathematicians struggled for centuries with the question of what, multiplied by itself, gives the answer -1 before one of them, Leonhard Euler, suggested that the best way to deal with the problem was to invent a new symbol (he chose i) and live with the consequences.

ECONOMIST: Beno?t Mandelbrot