By Philosophy, I mean that branch of heuretic science (the science of discovery,) which, in the first place, seeks categorical truth, and does not, like mathematics, content itself with demonstrating the truth of its discoveries conditionally upon the absolute acceptance of the exact truth of postulates, conditions, or antecedents, for which that science does not in the least assume responsibility. Yet Philosophy, as I understand it, although it is a heuretic science of categorical truth, […] does not profess either by wider or by more refined observations to open to us any new experience whatever. On the contrary, all that it is to teach us, it is to teach by new reasonings based [on] the common experience of all mankind, or at any rate upon what nobody in the world has any doubt about, or can possibly bring himself to doubt of it.