From the species of Belief constituted by an inference from experience, Hume, by an easy transition, passes on to Belief in general, which he defines to be 'nothing but a more vivid, lively, forcible, firm, steady conception of an object, than what the imagination alone is ever able to attain,' referring, by way of illustration, to an animal with the head of a man and the body of a horse, which anyone can imagine, but no one can believe in, and desiring us apparently to suppose that if our groom were to come and tell us that he had found a centaur feeding in the paddock beside our favourite saddle-horse, our sole reason for believing in the horse and for not believing in the centaur would be our greater ability to conceive the one than the other. That such a definition should for a moment have satisfied its author's curiosity, is itself a psychological curiosity which must not, however, be suffered to detain us. Whoever, not content with knowing perfectly well what belief is, desires to have his knowledge of it set down in writing, should read the admirable notes on the subject, with which Mr. John Mill and Mr. Bain have enriched the last edition of Mr. James Mill's 'Analysis of the Human Mind.' Most readers, however, will probably be disposed to avail themselves here of a rather favourite phrase of Hume himself, and to plead that, 'if we agree about the thing, it is needless to dispute about terms;' and it is not unlikely that such of them as may have formed their notion of metaphysical discussions in general from the specimens given above, may go so far as to hint a doubt whether any of the nice verbal distinctions which metaphysicians so much affect, are really worth the trouble required to understand them. Nor would anyone, perhaps, be much the worse for acting upon this suspicion, provided that, in accordance with it, he kept altogether aloof from the studies which it disparages. His ideas need not be the less clear because he neither knows nor cares of what they are copies, nor whether they are copies of anything; nor will the order of their occurrence be at all affected in consequence of his being similarly careless, whether that order is or is not governed by a _law_ of association; neither need his inferences from experience be the less sound in consequence of his never having enquired how or why they are deduced. But although the most absolute ignorance and corresponding indifference about these and kindred topics may not tend in the least to disqualify him for performance of the whole duty of man, it is not the less important that, if he do care to know aught about them, his knowledge should be exact, for there is no knowing beforehand how luxuriantly the minutest germ of theoretical error may ramify in practice, or into what substantive quagmire trust in deceitful shadows may lead. These respectable aphorisms may be beneficially borne in mind during perusal of what is about to be said.