THE ADVANCEMENT OF LEARNING

Francis Bacon's work The Advancement of Learning.

It influenced the taxonomic structure of Jean le Rond d'Alembert and Denis Diderot's immensely influential Encyclopédie, and is considered by Bacon's biographer-essayist Catherine Drinker Bowen as a pioneering essay in defence of empirical philosophy.

So, just as Tennis is a game of no value in and of itself, but of enormous utility in that it develops a quick eye and a body able to put itself in any situation, so, in mathematics, collateral, intervenient use is no less worthwhile than principle and planned use.