The Essays of Adam Smith · Adam Smith
ANCIENT LOGICS AND METAPHYSICS.
Aristotle, who seems in many things original, and who endeavoured to seem to be so in all things, added the principle of privation to those of matter and form, which he had derived from the ancient Pythagorean school. When Water is changed into Air, the transmutation is brought about by the material principle of those two elements being deprived of the form of Water, and then assuming the form of Air. Privation, therefore, was a third principle opposite to form, which entered into the generation of every Species, which was always from some other Species. It was a principle of generation, but not of composition, as is most obvious. The Stoics, whose opinions were, in all the different parts of philosophy, either the same with, or very nearly allied to those of Aristotle and Plato, though often disguised in very different language, held, that all things, even the elements themselves, were compounded of two principles, upon one of which depended all the active, and upon the other all the passive, powers of these bodies. The last of these, they called Matter; the first, the Cause, by which they meant the very same thing which Aristotle and Plato understood, by their specific Essences. Matter, according to the Stoics, could have no existence separate from the cause or efficient principle which determined it to some particular class of things. Neither could the efficient principle exist separately from the material, in which it was always necessarily embodied. Their opinion, therefore, so far coincided with that of the old Peripatetics. The efficient principle, they said, was the Deity. By which they meant, that it was a detached portion of the etherial and divine nature, {404} which penetrated all things, that constituted what Plato would have called the Specific Essence of each individual object; and so far their opinion coincides pretty nearly with that of the latter Platonists, who held, that the Specific Essences of all things were detached portions of their created deity, the soul of the world; and with that of some of the Arabian and Scholastic Commentators of Aristotle, who held that the substantial forms of all things descended from those Divine Essences which animated the Celestial Spheres. Such was the doctrine of the four principal Sects of the ancient Philosophers, concerning the Specific Essences of things, of the old Pythagoreans, of the Academical, the Peripatetic, and the Stoical Sects.
As this doctrine of Specific Essences seems naturally enough to have arisen from that ancient system of Physics, which I have above described, and which is, by no means, devoid of probability, so many of the doctrines of that system, which seems to us, who have been long accustomed to another, the most incomprehensible, necessarily flow from this metaphysical notion. Such are those of generation, corruption, and alteration; of mixture, condensation, and rarefaction. A body was generated or corrupted, when it changed its Specific Essence, and passed from one denomination to another. It was altered when it changed only some of its qualities, but still retained the same Specific Essence, and the same denomination. Thus, when a flower was withered, it was not corrupted; though some of its qualities were changed, it still retained the Specific Essence, and therefore justly passed under the denomination of a flower. But, when, in the further progress of its decay, it crumbled into earth, it was corrupted; it lost the Specific Essence, or substantial form of the flower, and assumed that of the earth, and therefore justly changed its denomination. The Specific Essence, or universal nature that was lodged in each particular class of bodies, was not itself the object of any of our senses, but could be perceived only by the understanding. It was by the sensible qualities, however, that we judged of the Specific Essence of each object. Some of these sensible qualities, therefore, we regarded as essential, or such as showed, by their presence or absence, the presence or absence of that essential form from which they necessarily flowed. Others were accidental, or such whose presence or absence had no such necessary consequences. The first of these two sorts of qualities was called Properties; the second, Accidents.
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