If you sense a deep human need, then you go back to all the basic science. If there is some missing, then you try to do more basic science and applied science until you get it. So you make the system to fulfill that need, rather than starting the other way around, where you have something and wonder what to do with it.

As quoted in Proceedings of the American Philosophical Society, Vol. 146, no. 1, (March 2002), p. 115