# Section VIII: Of the Causes of Belief explained — A Treatise of Human Nature > Chapter companion for A Treatise of Human Nature by David Hume. ## What happens Hume investigates the origin of belief, proposing that it arises from a present impression that communicates vivacity to related ideas. He supports this with experiments on resemblance and contiguity, and argues that belief is a product of custom and habit, not reason. He concludes that all probable reasoning is a species of sensation, and that past experience operates insensibly to produce belief. ## Themes in this chapter ### Custom and General Rules Hume argues that belief is derived from custom and habit, not from rational inference, and that past experience operates insensibly. ### Empiricism and the Primacy of Impressions The chapter emphasizes the role of present impressions in enlivening ideas and producing belief, highlighting the empirical basis of knowledge. ## Character check-ins ### David Hume Author and narrator, presenting his theory of belief and its causes. ## Key lines > When any impression becomes present to us, it not only transports the mind to such ideas as are related to it, but likewise communicates to them a share of its force and vivacity. A present impression not only leads the mind to related ideas but also transfers some of its own liveliness to them. _This is the core principle Hume sets out to prove._ > All probable reasoning is nothing but a species of sensation. All reasoning about probabilities is essentially a matter of feeling, not logic. _Hume concludes that belief is based on sentiment, not rational deduction._ > The custom operates before we have time for reflection. Habit works so quickly that we are not aware of it before it influences our thinking. _This illustrates the insensible operation of custom in producing belief._ ## Links - HTML: https://www.betterreads.online/discover/a_treatise_of_human_nature_se/chapters/section-viii-of-the-causes-of-belief - Book: https://www.betterreads.online/discover/a_treatise_of_human_nature_se - All chapters: https://www.betterreads.online/discover/a_treatise_of_human_nature_se/chapters