A large part of mathematics which becomes useful developed with absolutely no desire to be useful, and in a situation where nobody could possibly know in what area it would become useful; and there were no general indications that it ever would be so. By and large it is uniformly true in mathematics that there is a time lapse between a mathematical discovery and the moment when it is useful; and that this lapse of time can be anything from thirty to a hundred years, in some cases even more; and that the whole system seems to function without any direction, without any reference to usefulness, and without any desire to do things which are useful.

John von Neumann (1903-1957) Hungarian-American mathematician, physicist, inventor, polymath [János "Johann" Lajos Neumann]

“The Role of Mathematics in the Sciences and in Society,” Speech, Princeton (1954)
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