What is the theme in An Essay Concerning Human Understanding by John Locke?

One of the key themes of this work is the defense and articulation of an empiricist theory of knowledge. Although Hobbes had previously developed something like an empiricist theory of knowledge, his theory, though brilliant, is idiosyncratic. Locke is properly seen as the father of modern empiricism, the approach to philosophy followed by Hume, Berkeley, Mill, Ayer, Quine and many other philosophers up until the present day. Indeed, some form of empiricism is the dominant approach to philosophy in the English-speaking world. Locke's approach is developed in this Essay.