The initial groundwork for Berkeley's position is the truism
             that the materialist is a skeptic. In the writing of his three
             dialogues, Berkeley develops two characters: Hylas (the materialist)
             and Philonous (Berkeley himself). Philonous draws upon one central
             supposition of the materialist to formulate his argument of skepticism
             against him; this idea is that one can never perceive the real essence
             of anything. In short, the materialist feels that the information
             received through sense experience gives a representative picture of
             the outside world (the representative theory of perception), and one
             can not penetrate to the true essece of an object. This makes logical
             sense, for the only way to perceive this real essence would be to
             become the object itself! Although the idea is logical, it does
             contain a certain grounding for agnosticism. Let the reader consider
             this: if there is no way to actually sense the true material essence
             of anything, and all knowledge in empiricism comes from the senses,
             then the real material essence can not be perceived and therefore it
             can not be posited. This deserves careful consideration, for the
             materialist has been self-proclaimed a skeptic! If the believer in
             this theory were asked if a mythical beast such as a cyclops existed
             he would most certainly say no. As part of his reply he might add that
             because it can not be sensed it is not a piece of knowledge. After
             being enlightened by the above proposed argument, though, that same
             materialist is logically forced to agree that, because the "material
             substratum1" itself can not be sensed, its existence can not be
             treated as knowledge. The materialist belief has, in effect, become as
             futile as proving that the cyclops exists; his ideas have lead him
             Having proven that the materialist is, at best, a doubter,
             Berkeley goes on to offer the...