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"Three Dialogues between Hylas and Philonous is a book written by George Berkeley in 1713.

"The most important concepts in the Three Dialogues are: perceptual relativity, the conceivability ("master") argument and Berkeley's phenomenalism. The perceptual relativity argument is that the same object can appear to have different characteristics (e.g. shape) depending on the observer's perspective. Since objective features of objects cannot change without an inherent change in the object itself, then shape must not be an objective feature.

"Hylas is understood to represent John Locke, Berkeley's primary contemporary philosophical adversary. A Hylas is featured in Greek mythology: in the Dialogues the name Hylas is derived from an ancient Greek word for matter which Hylas argues for in the dialogue.

"Philonous translates as lover of mind and represents Berkeley himself."

"René Descartes (1596-1650) is one of the most important Western philosophers of the past few centuries. During his lifetime, Descartes was just as famous as an original physicist, physiologist and mathematician. But it is as a highly original philosopher that he is most frequently read today. He attempted to restart philosophy in a fresh direction. Descartes' work was influential, although his studies in physics and the other natural sciences much less so than his mathematical and philosophical work. Throughout the 17th and 18th Centuries, Descartes' philosophical ghost was always present; Locke, Hume, Leibniz and even Kant felt compelled to philosophical entanglement with this intellectual giant. For these reasons, Descartes is often called the "father" of modern philosophy.  The two most widely known of Descartes' philosophical ideas are those of a method of hyperbolic doubt, and the argument that, though he may doubt, he cannot doubt that he exists. The first of these comprises a key aspect of Descartes' philosophical method. As noted above, he refused to accept the authority of previous philosophers - but he also refused to accept the obviousness of his own senses. In the search for a foundation for philosophy, whatever could be doubted must be rejected. He resolves to trust only that which is clearly and distinctly seen to be beyond any doubt. In this manner, Descartes peels away the layers of beliefs and opinions that clouded his view of the truth. But, very little remains, only the simple fact of doubting itself, and the inescapable inference that something exists doubting, namely Descartes himself."