The main Business of Natural Philosophy is to argue from Phaenomena without feigning Hypotheses, and to deduce Causes from Effects till we come to the very first Cause, which certainly is not mechanical; and not only to unfold the Mechanism of the World, but chiefly to resolve these, and to such like Questions.

Opticks: Or, A Treatise of the Reflections, Refractions, Inflections and Colours of Light.... (ed. 1718)