David Hume, an empiricist philosopher, takes on perhaps one of the most challenging of conceivable problems in An Enquiry Concerning Human Understanding. Moving beyond Descartes classic statement, I think, therefore I am, Hume addresses issues of knowing that fall outside the realms of active thought or incremental learning. While innumerable philosophers discuss various aspects of experience, Hume stands alone in his successful treatise on the nature of experience itself.