Supply and Demand — Hubert D Henderson

The recognition of order in anybranch of natural phenomena is but the prelude to the formulation of a set of laws the simpler as the order is more universal which describe and as we say explain it Thus the perception of the even elliptical courses of the heavenly bodies led to the statement of the law of gravitation and the laws of motion In economics similar laws have long since been enunciated and have proved themselves such valuable instruments for the understanding of the daily problems of the workaday world that they have been woven into the texture of our ordinary speech and thought