An Enquiry Concerning Human Understanding is a book by the Scottish empiricist philosopher David Hume, published in English in 1748. It was a revision of an earlier effort, Hume's A Treatise of Human Nature, published anonymously in London in 1739-40. Hume insists that the conclusions of the Enquiry will be very powerful if they can be shown to apply to animals and not just humans. He believed that animals were able to infer the relation between cause and effect in the same way that humans do through learned expectations. The memory is a faculty that conjures up ideas based on experiences as they happened.