After beholding and examining any material object, our knowledge respecting it exists in two different forms. Some facts exist in the brain in a verbal form, as known, but not conceived, as, for instance, that it was heavy or light, that it was eight inches and a quarter long, etc., of which length we cannot have accurate conception, but only such a conception as might attach to a length of seven inches or nine; and which fact we may recollect without any conception of the object at all. Other facts respecting it exist in the brain in a visible form, not always visible, but voluntarily visible, as its being white, or having such and such a complicated shape, as the form of a rose-bud, for instance, which it would be difficult to express verbally, neither is it retained by the brain in a verbal form, but a visible one, that is, when we wish for knowledge of its form for immediate use, we summon up a vision or image of the thing; we do not remember it in words, as we remember the fact that it took so many days to blow, or that it was gathered at such and such a time. The knowledge of things retained in this visible form is called conception by the metaphysicians, which term I shall retain; it is inaccurately called imagination by Taylor, in the passage quoted by Wordsworth in the preface to his poems, not but that the term imagination is etymologically and rightly expressive of it, but we want that term for a higher faculty. Sec. 2. How connected with verbal knowledge. There are many questions respecting this faculty of conception of very great interest, such as the exact amount of aid that verbal knowledge renders so visible, (as, for instance, the verbal knowledge that a flower has five, or seven, or ten petals, or that a muscle is inserted at such and such a point of the bone, aids the conception of the flower or the limb;) and again, what amount of aid the visible knowledge renders to the verbal, as for instance, whether any one, being asked a question about some animal or thing, which instantly and from verbal knowledge he cannot answer, may have such power of summoning up the image of the animal or thing as to ascertain the fact, by actual beholding, (which I do not assert, but can conceive to be possible;) and again, what is that indefinite and subtile character of the conception itself in most men, which admits not of being by themselves traced or realized, and yet is a sure test of likeness in any representation of the thing; like an intaglio, with a front light on it, whose lines cannot be seen, and yet they will fit one definite form only, and that accurately; these and many other questions it is irrelevant at present to determine,[50] since to forward our present purpose, it will be well to suppose the conception, aided by verbal knowledge, to be absolutely perfect, and we will suppose a man to retain such clear image of a large number of the material things he has seen, as to be able to set down any