As the author of several well-known works such as "Treatise of Human Nature" (1739-1740), "An Enquiry Concerning Human Understanding" (1748) and "Dialogues Concerning Natural Religion," David Hume is one of the most influential figures to hail from Great Britain (Morris). Often grouped with John Locke and George Berkeley, Hume is known as the last of the great triumvirate of "British empiricists" (Morris). Empiricism is a theory of knowledge branching from the field of epistemology that asserts the idea that knowledge arises via sensual experience. Empiricism stresses the role of experience and evidence in the formation of ideas over the notion of reason. Several eminent figures in history from philosopher Immanuel Kant to economist Adam Smith to biologist/naturalists Charles Darwin and Thomas Huxley credit David Hume as being the central influence in their writings. Hume's strong empirical views are clearly evident in his book, An Inquiry Concerning Human Understanding. He begins by comparing the two different manners of human understanding, which fall under the broad category of Moral philosophy. Hume believes the first manner to be "easy and obvious philosophy" by considering "man chiefly born for action" while the second aspect is considered "accurate and abstruse" as it "considers man in light of reason" (Hume 1). Rather than direct our conduct/actions, the abstruse form of philosophy regards "human nature as a subject of speculation" in hopes of finding the "principles that regulate human understanding" (Hume 1). This form of perplexing philosophy can also be called metaphysics, and throughout the greater portion of the text, Hume attempts to defend it against the critics who always belittle it and consider the "easy and obvious philosophy" the ideal and more acceptable one. .
In an attempt to start explaining the complex nature of human understanding, Hume proposes a division of all perceptions of the mind into two species, which can be "distinguished by their different degrees of force and vivacity.