Nor can these Lectures be justly deemed superfluous even as a literary work. We have, indeed, a History of Philosophy, or rather a folio volume so called, by STANLEY, and ENFIELD'S Abridgment of the massive and voluminous BRUCKER. But what are they? Little more, in fact, than collections of sentences and extracts, formed into separate groups under the several names, and taken (at first or second hand) from the several writings of individual philosophers, with no _Principle_ of arrangement, with no _method_, and therefore without unity and without progress or completion. Hard to be understood as detached passages, and impossible to be remembered as a whole, they leave at last on the mind of the most sedulous student but a dizzy recollection of jarring opinions and wild fancies. Whatever value these works may have as books of reference, so far from _superseding_, they might seem rather to _require_, a work like the present, in which the accidental influences of particular periods and individual genius are by no means overlooked, but which yet does in the main consider Philosophy historically, as an essential part of the history of man, and as if it were the striving of a single mind, under very different circumstances indeed, and at different periods of its own growth and development; but so that each change and every new direction should have its cause and its explanation in the errors, insufficiency or prematurity of the preceding, while all by reference to a common object is reduced to harmony of impression and total result. Now this object, which is one and the same in all the forms of Philosophy, and which alone constitutes a work _Philosophic_, is--the origin and primary laws (or efficient causes) either of the WORLD, man included (which is _Natural_ Philosophy)--or of Human Nature exclusively, and as far only as it is _human_ (which is _Moral_ Philosophy). If to these we subjoin, as a third problem, the question concerning the sufficiency of the human reason to the solution of both or either of the two former, we shall have a full conception of the sense in which the term Philosophy is used in this Prospectus and the Lectures corresponding to it.