VI. The true absolute mass of a body is the number of primitive elements it contains.
VII. The primitive elements are of two kinds, some of them always and everywhere attractive, others always and everywhere repulsive. The matter, however, is the same in both kinds, and bears the same relation to its form, whether this be of an attractive or of a repulsive nature.
VIII. There are no other powers in the primitive elements than that of attracting and that of repelling.
IX. All primitive elements have a sphere of activity, throughout which they constantly act according to the Newtonian law—that is, in the inverse ratio of the squared distances, even when the distance is molecular; and no distance, however great, can be designated where the action of an element will not have a finite intensity.
X. The active power of primitive elements cannot be exerted in the immediate contact of matter with matter, distance being an essential condition of all locomotive actions.
XI. The elementary power acts immediately on all distant matter throughout its sphere, independently of any material medium of transmission or communication. Movement, however, cannot be propagated without a material medium.
XII. The term from which the action of any given element is directed, and the term in which the same element receives the motion caused by other elements, is one and the same, viz., the real centre of its sphere of activity; and it is called the matter. The act from which such a centre receives its first existence is called the substantial form; and it has a spherical character, inasmuch as it constitutes a virtual indefinite sphere.
XIII. The essence of a primitive element of matter is by no means a mystery. The essential definition of such an element is “a substance fit to cause and to receive mere local motion.”
XIV. Inertia is an essential property of material substance, no less than activity and passivity. Inertia admits of no degrees.
XV. The so-called “force of inertia” is neither the inertia itself nor any special motive power; but it merely expresses a certain exercise of the elementary powers dependent on the inertia of the matter acted on; for bodies, on account of their inertia, cannot leave their place before they have received in all their parts a suitable velocity. Hence while such a velocity is being communicated to a body, the body which is acted on cannot yield its place to the impinging body; and consequently, [pg 678] during the struggle of two bodies, the one which impinges loses a quantity of movement equal to that which it imparts to the mass impinged upon. The loss of movement in the impinging body is therefore caused, not by the inertia of the body impinged upon, but by its elementary powers as exercised by it during the reception of the momentum.