[272] Ibid. iv. p. 141, a. 24-b. 2.
The locus here indicated by this general feature is one, but it includes a number of varieties.[273] More known, or less known, it should first be observed, has two distinct meanings: either more or less known absolutely (by nature); or more or less known to us. Absolutely, or by nature, the point is better known than the line; the line, than the superficies; the superficies, than the solid; the prius, than the posterius. But to us the reverse is true. The solid, as object of sensible perception, is earlier known and more known than the superficies; the superficies, than the line; the line, than the point; the posterius, than the prius. To us means to the bulk of mankind: absolutely or by nature refers to the instructed, superior, teaching and expository, intellects.[274] There may be some cases in which the notius nobis coincides and is identical with the notius naturâ;[275] but, as a rule, the two are distinct, and the one is the inverse of the other. A genuine and perfect definition is one which enunciates the essence of the Species through Genus and Differentiæ, which are both of them absolutely prior and more knowable than the Species, since, if they be supposed non-existent, the Species is nowhere to be found. No man can know the Species without knowing its Genus and Differentiæ; but you may know the Genus and Differentiæ without knowing the Species; hence the Species is more unknowable than they are.[276] This is the true scientific definition; but there are persons incapable of acquiring knowledge by means of it. To these persons, an imperfect explanation or quasi-definition must be given, by means of matters knowable to them.[277] Those, however, who regard such imperfect explanations as true definitions, must be reminded that, upon that hypothesis, we should be compelled to admit many distinct definitions of the same definiend. For individuals differ from each other in respect to what is more knowable: what is more so to one man is not more so to another. Indeed the same man differs from himself on this point at different periods: to the early and untrained mind objects of sensible perception are the most knowable; but, when a man has been improved by training and instruction, the case is reversed, and the objects of intellect become the most familiar to his mind.[278] To define properly, therefore, we must enunciate, not the notiora nobis but, the notiora naturâ or simpliciter; understanding by this last phrase, not what is more knowable to all actual men but, what is more knowable to men of well-trained and well-constituted intellect; just as, when we speak of the wholesome, we mean what is wholesome to the well-constituted body.[279] These conditions of Definition you must thoroughly master, and apply to each debate as the occasion may require. Your task in refuting an alleged definition will be the easiest in those cases where it conforms to neither of the above conditions; that is, when it enunciates neither what is notius naturâ nor what is notius nobis.[280]
[273] Ibid. v. p. 142, b. 20.
[274] Topic. VI. iv. p. 141, b. 3-14.
[275] Ibid. b. 22.
[276] Ibid. b. 25.
[277] Ibid. b. 16.
[278] Ibid. b. 34.
The general mental fact here noticed by Aristotle may be seen philosophically stated and explained in the volume of Professor Bain on the Emotions and the Will. (Chapter on Consciousness, sect. 19, p. 581, 2nd ed.)
“A sensation is, under any view of it, a conscious element of the mind. As pleasure or pain, we are conscious in one way; as discrimination, we are conscious in the other way, namely, in a mode of neutral excitement. — But this is not all. After much contact with the sensible world, a new situation arises, and a new variety of the consciousness, which stands in need of some explanation. When a child experiences for the first time the sensation of scarlet, there is nothing but the sensibility of a new impression more or less intense.… It is very difficult for us to realize or define this original shock, our position in mature life being totally altered. It is the rarest thing for us then to come under a radically new impression; and we can only, by help of imperfect analogies, form an approximate conception of what happens at the first shock of a discriminative sensation. The process of engraining these impressions on the mind after repetition, gives to subsequent sensations quite a different character as compared with the first. The second shock of scarlet, if it stood alone, would doubtless resemble the preceding; but such is the nature of the mind, that the new shock will not stand alone, but restores the notion or idea or trace that survived the former. The sensation is no longer the primitive stroke of surprise, but a coalition of a present shock with all that remains of the previous occasions. Hence it may properly be said, when we see, or hear, or touch, or move, that what comes before us is really contributed more by the mind itself than by the object present. The consciousness is complicated by three concurring elements — the new shock, the flash of agreement with the sum total of the past, and the feeling of that past as revived in the present. In truth, the new sensation is apt to be entirely over-ridden by the old; and, in place of discriminating by virtue of our susceptibility to what is characteristic in it, our discrimination follows another course. For example, if I have before me two shades of colour, instead of feeling the difference exactly as I am struck at the moment, my judgment resorts to the round-about process of first identifying each with some reiterated series of past impressions; and, having two sum-totals in my mind, the difference that I feel is between those totals. If I made a mistake, it may be attributed not so much to a wrong act of discrimination, as to a wrong act of identification. — All sensations, therefore, after the first of each kind, involve a flash of recovery from the past, which is what really determines their character. The present shock is simply made use of as a means of reviving some one past in preference to all others; the new impression of scarlet is in itself almost insignificant, serving only as the medium of resuscitating the cerebral condition resulting from the united force of all the previous scarlets. — Sensation thus calls into operation the two great intellectual laws, in addition to the primitive sensibility of difference. — When we consider ourselves as performing the most ordinary act of seeing or hearing, we are bringing into play those very functions of the intellect that make its development and its glory in its highest manifestations.�