The Enlightenment thinker presents his empirical approach to epistemology in this foundational text of modern philosophy. First published in 1748, David Hume's An Enquiry Concerning Human Understanding presents a persuasive argument in favor of the view that all human knowledge derives from experience. Discarding the notion of innate ideas and building on the views of English philosopher John Locke, this work delivered a serious blow to religious doctrine of the age, making it as controversial as it was influential. Expounding on the empiricist stance, Hume posits the building blocks of all thought, starting with the sensations we receive from direct experience, which he calls impressions; our memories of those impressions, which he calls ideas; and the different ways we perceive those ideas in relation to one another. From here, Hume contemplates a range of topics, including probability, free will, the problem of induction, and the reliability of human testimony.