Leibniz

"THE GAME CALLED SOLITAIRE pleases me much," the great
German mathematician Gottfried von Leibniz wrote in a letter
in 1716. "I take it in reverse order. That is to say, instead
of making a figure according to the rules of the game,
which is to jump to an empty place and remove the piece over
which one has jumped, I thought it better to reconstruct
what had been demolished by filling an empty hole over which
one has leaped. In this way one may set oneself the task of
forming a given figure if that is possible, as it certainly is
if it can be destroyed. But why all this? you ask. I reply: to
perfect the art of invention. For we must have the means
of constructing everything which is found by the exercise of
reason."

in Martin Gardner's "The Unexpected Hanging"