The Commens Dictionary
Quote from ‘Lowell Lectures. 1903. Lecture 3’
…if we conceive a science, not as a body of ascertained truth, but, as the living business which a group of investigators are engaged upon, which I think is the only sense which gives a natural classification of sciences, then we must include under mathematics everything that is an indispensible part of the mathematician’s business; and therefore must include the formulation of his hypotheses as well as the tracing out of their consequences.