FORM, in Physics, denotes the manner of being peculiar to each body; or that which constitutes it such a particular body, and distinguishes it from every other. But Mr Harris uses the term form in another sense, as an efficient animating principle; to which he supposes Ovid to refer in the first lines of his Metamorphoses.

In novafert animus mutatas dicere formas, Corpora.

These animating forms are not of themselves objects either of the ear or of the eye; but their nature or character is understood in this, that were they never to exert their proper energies on their proper subjects, the marble on which the sculptor exercises his art would remain for ever shapeless, and the harp from which the harper calls forth sounds would remain for ever silent.

Substantial forms seem to have been first broached by the followers of Aristotle, who thought matter, under different modes or modifications, not sufficient to constitute different bodies, but that something substantial was necessary to set them at a greater distance, and thus introduced substantial forms, on the footing of souls, which specify and distinguish animals. What led to this erroneous notion were the circumstances of life and death. For observing that, as soon as the soul had departed out of a man, all motion, respiration, nutrition, and other animal functions, immediately ceased, they concluded that these functions depended on the soul, and consequently that the soul was the form of the animal body, or that which constituted it such; indeed nobody doubted that the soul was a substance independent of matter; and hence it was concluded that the forms of other bodies were to be equally substantial. But to this it is answered, that though the soul be that by which man is man, and consequently the form of the human body as human, yet it does not follow that it is properly the form of this body of ours, as it is a body, or of the several parts thereof, ∞nsidered as distinct from one another. For those several parts have their proper forms so closely connected with their matter, that it remains inseparable therefrom long after the soul has quitted the body; thus flesh has the form of flesh, bone of bone, and so forth, long after the soul is removed, as well as before. The truth is, the body does not become incapable of performing its accustomed functions because the soul has deserted it; but the soul takes its leave because the body is no longer in a condition to perform its functions.

The ancient and modern corpuscular philosophers, therefore, with the Cartesians, exclude the notion of substantial forms, and show, by many arguments, that the form is only the modus or manner of the body in which it ;s inherent.

And as there are only three primary modes of matter, figure, rest, or motion, with two others arising therefrom, magnitude and situation, the form of all bodies they hold to consist in these modes, and suppose the variations which they are capable of sufficient to present all the variety observable in bodies.

Forms are usually distinguished into essential and accidental. Though the five modes above mentioned, generally taken, be adventitious, yet to this or that body, as to fire or water, they are essential. Thus it is accidental to iron to have this or that magnitude, figure, or situation, since it might exist in different ones; yet to a knife or hammer, the figure, magnitude, and position of parts, which constitute it a hammer or knife, are essential, and they cannot exist or be conceived without these. Hence it is inferred, that though there be no substantial, yet there are essential forms, by which the several species of bodies become what they are, and are distinguished from all others. Accidental forms are those really inherent in bodies, but in such manner as that the body may exist in all its perfection without them; such as whiteness in a wall, heat in water, a figure of a man in wax, and so on.

Form, in carpentry, is used to denote the long seats or benches in the choirs of churches or in schools, for the priests, prebends, religious persons, or scholars, to sit on. Du Cange supposes the name to be derived from this, that the backs of the seats were anciently enriched with figures of painting and sculpture, called in Latin forma et typi. In the life of St William of Roschild, we meet with forma as signifying a seat for an ecclesiastic, or religious person, in a choir; and in that of St Lupicin, we find formula used in the same sense. In the rule of the monastery of St Caesarea, the man who presides over the choir is called the occupant of the first form or seat.