On the Fourfold Root of the Principle of Sufficient...

The fundamental essence of our Reason or thinking faculty is, as we have seen, the power of abstraction, or the faculty of forming conceptions: it is therefore the presence of these in our consciousness which produces such amazing results. That it should be able to do this, rests mainly on the following grounds.

It is just because they contain less than the representations from which they are drawn, that conceptions are easier to deal with than representations; they are, in fact, to these almost as the formula of higher arithmetic to the mental operations which give rise to them and which they represent, or as a logarithm to its number. They only contain just the part required of the many representations from which they are drawn; if instead we were to try to recall those representations themselves by means of the imagination, we should, as it were, have to lug about a load of unessential lumber, which would only embarrass us; whereas, by the help of conceptions, we are enabled to think only those parts and relations of all these representations which are wanted for each individual purpose: so that their employment may be compared to doing away with superfluous luggage, or to working with extracts instead of plants themselves—with quinine, instead of bark. What is properly called thinking, in its narrowest sense, is the occupation of the intellect with conceptions: that is, the presence in our consciousness of the class of representations we now have before us. This is also what we call reflection: a word which, by a figure of speech borrowed from Optics, expresses at once the derivative and the secondary character of this kind of knowledge. Now it is this thinking, this reflection, which gives man that deliberation, which is wanting in animals.

For, by enabling him to think many things under one conception, but always only the essential part in each of them, it allows him to drop at his pleasure every kind of distinction, consequently even those of Time and of Space, and thus he acquires the power of embracing in thought, not only the past and the future, but also what is absent; while animals are in every respect strictly bound to the present. This deliberative faculty again is really the root of all those theoretical and practical achievements which give man so great a superiority over animals; first and foremost, of his care for the future while taking the past into consideration; then of his premeditated, systematic, methodical procedure in all undertakings, and therefore of the co-operation of many persons towards a common end, and, by this, of law, order, the State, &c. &c.—But it is especially in Science that the use of conceptions is important; for they are, properly speaking, its materials. The aims of all the sciences may, indeed, in the last resort, be reduced to knowledge of the particular through the general; now this is only possible by means of the dictum de omni et nullo, and this, again, is only possible through the existence of conceptions. Aristotle therefore says: ἄνευ μὲν γὰρ τῶν καθόλου οὐκ ἔστιν ἐπιστήμην λαβεῖν[119] (absque universalibus enim non datur scientia). Conceptions are precisely those universalia, whose mode of existence formed the argument of the long controversy between the Realists and Nominalists in the Middle Ages.