A writer in the _Encyclopedia Metropolitana_ describes him as "the one, perhaps, whose heart was most free from scepticism, and whose understanding was most prone to it." Berkeley is here dealt with as one specially contributing to the growth of sceptical thought, and not as an Idealist only. Arthur Collier published, about the same time as Berkeley, several works in which absolute Idealim is advocated. Collier and Berkeley were mouthpieces for the expression of an effort at resistance against the growing Spinozistic school. They wrote against substance assumed as the "noumenon lying underneath all phenomena--the substratum supporting all qualities--the something in which all accidents inhere." Collier and his writings are almost unknown; Berkeley's name has become famous, and his arguments have served to excite far wider scepticism than have those of any other Englishman of his age. Most religious men who read him misunderstand him, and nearly all misrepresent his theory. Hume, speaking of Berkeley, says, "Most of the writings of that very ingenious philosopher form the best lessons of scepticism which are to be found, either among the ancient or modern philosophers, Bayle not excepted. He professes, however, in his title page (and undoubtedly with great truth) to have composed his book against the sceptics, as well as against the Atheists and Freethinkers. But that all his arguments, though otherwise intended, are in reality merely sceptical, appears from this, that they admit of no answer, and produce no conviction," Berkeley wrote for those who "want a demonstration of the existence and immateriality of God, or the natural immortality of the soul," and his philosophy was intended to check materialism. The key-note ot his works may be found in his declaration, "The only thing whose existence I deny, is that which philosophers call Matter or corporeal substance." The definition given by Berkeley of matter is one which no materialist will be ready to accept, i.e.f "an inert, senseless substance in which extension, figure, and motion do actually exist." The "Principles of Human Knowledge" is the work in which Berkeley's Idealism is chiefly set forth, and many have been the volumes and pamphlets written in reply. Whatever might have been Berkeley's intention as to refuting scepticism, the result of his labours was to increase it in no ordinary degree; Dr. Pye Smith thug summarises Berkeley's views:--"He denied the existence of matter as a cause of our perceptions, but firmly maintained the existence of created and dependent spirits, of which every man is one; that to suppose the existence of sensible qualities and of a material world, is an erroneous deduction from the fact of our perceptions; that those perceptions are-nothing but ideas and thoughts in our minds; that these are produced in perfect uniformity, order, and consistency in all minds, so that their occurrence is according to fixed rules which may be called the