George Berkeley had an important impact on the Enlightenment. Mostly his controversial thoughts about immaterialism that contrasted the others materialist thinkers, suck as Locke and Newton. Berkeley’s first important book was An Essay Towards a New Theory of Vision. In this book the immaterialism of his later philosophical writings first appears. In the Essay, Berkeley denied the belief of matter and supported the thesis by saying that matter has no objective existence.  In A Treatise Concerning the Principles of Human Knowledge (1710), and in his Three Dialogues Between Hylas and Philonous (1713), Berkeley argued that the materialist hypothesis is illogical, that an object without sensible qualities cannot be conceived, and sensible qualities cannot exist on material objects, since to be sensible is just to be perceived. A shape therefore cannot be conceived without a color or tactile quality to give it shape, and these latter qualities exist only in the activity of perception. In arguing for philosophical idealism, Berkeley extended empiricism beyond that of Locke, since Locke emphatically allowed that material objects could and must exist outside of immediate perception, a position that Berkeley found inconsistent with Locke’s own empiricism. Berkeley’s idealism therefore led him to deny the existence of matter, and in this regard he influenced the later idealisms of Fichte, Johann Gotlieb, Schopenhauer, and Bradley.