Among the greatest philosophers of science of all times one would surely have to include Aristotle, Descartes, Leibniz, Hume, and Kant. In an important sense Kant represents a culmination of this tradition on account of his strenuous attempts to provide an epistemological and metaphysical analysis appropriate to mature Newtonian science. There were, to be sure, significant developments in classical physics after Kant's death — e.g. Maxwell's electromagnetic theory — but these seemed more like completions of the Newtonian system than revolutionary subversions which would demand profound conceptual and philosophical revisions. It was only in 1905 that the first signs of fundamental downfall of classical physics began to be discernible; even though Planck's quantum hypothesis and the Michelson-Morley experiment had occurred earlier, their crucial importance was only later recognized.