If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning, concerning matter of fact and existence? No. Commit it then to flames: for it can contain nothing but sophistry and illusion.
David Hume (1711–1776), Scottish philosopher. Enquiries Concerning the Human Understanding and Concerning the Principles of Morals, sect. 12 ("Of the Academical or Sceptical Philosophy"), part 3, p. 165, ed. L. Selby-Bigge, M.A., 2nd edition, London, Oxford University Press (1902).