The Principles, published when the author was only twenty-six, is the mostsystematic of all of Berkeley's expositions of his theory of knowledge: it wasthe direct outgrowth of the Essay Towards a New Theory of Vision (1709), whichsought to ban­ish the metaphysical abstractions of Absolute Space and Extensionfrom philosophy, and was itself mainly concerned with the aboli­tion ofAbstract Matter and of the ontological and theological corollaries of thatconcept. The Dialogues treat of substantially the same subjects but are morefamiliar and elegant in form and are devoted in the main to the refutation ofthe most plausible popular and philosophical objections to the new doctrine.The two books mark a distinctively new epoch in philosophy and science, andtogether afford a comprehensive survey of Berkeley's doctrines, placing withinthe reach of every reader in remarkably brief compass opinions which haveprofoundly influenced the course of intellectual history. Works of this kindhave been almost invariably distinguished by their brevity, ""I had noinclinations is Berkeley's characteristic remark, ""to trouble the world withlarge volumes