2853. Such motion is not relative in kind, i. e. it does not affect several portions of the matter in reference to some other matter; but it affects the whole matter internally, or its atoms, so that all matter may remain in its place and yet every atom of it be moved.

2854. This motion is like the motion of heat in the matter. By it heat is excited. For internal motion of the atoms, when aroused by polarity, so that every atom enters into a state of motion against the other, is a discharging of the poles, and consequently development of heat.

2855. This internal motion has, however, been produced by an external; for the external motion acts by contact, and this is a process of polarization. Now, the interior of a mass is only moved by repeated contact, or through the restlessness of polarization and by a proper amount of force, or one which is proportional to the mechanical resistance of the mass to be excited. The last of these is the stroke or blow, the first the vibration of the body. By vibration or oscillation only can a body be internally polarized; for, if it does not oscillate upon the shock being applied, it is still indeed set in motion, but "en masse," so that the internal parts remain in a state of rest.

2856. Oscillation is distinguished from continuous or progressive motion by its affecting the atoms of the body, while the latter acts upon the body itself. Through the vibration heat is engendered, because the poles are free and the matter passes over into æther.

2857. Vibration must endure the longest in solid bodies, and thus in that which belongs to the earth. Among these the hard bodies must take precedence, because the soft are of an aqueous nature. Among the hard bodies again the heaviest must vibrate most effectually, because they offer a longer resistance, and do not yield so soon as light bodies to the effort made at separation. The purest representative of the earth-element or the metal is thus the best instrument or means of vibration, and consequently the object of the motor sense.

2858. Thus as the salt of the earth-element is the object of taste, and as the resin of the earth-element is the object of smell, so would the metal be the object of this motor sense.

2859. But no sense-object is without its medium for transmission, except in the case of the sense of feeling or touch. The salt is only tasted by means of the water, the Inflammable only smelt by means of the air; the metal's primary motion could not therefore be perceived directly by the auditory sense. It must be propagated through the medium which ranks next to the heat, and whose atoms insinuate themselves most easily into those of the vibrating body—thus through the air. Man perceives the primary motion, in which things tend to resolve themselves into æther, through the air. By the metal, or by every vibrating body, the vibration of the air is communicated.

2860. This vibration is not, however, a general movement to and fro, but a dissolution of the material bands. This dissolution can only take place according to the laws of the primary motion. They are rigidified in the solid masses as crystalline forms. Every law of motion is a crystalline form which has become free or spiritually manifested. Through the vibration forms are engendered in bodies, which are commensurate with the substance and form of the mass and the degree of vibration. These forms, being as it were the ghosts or phantoms of crystals, are called sonorous figures.

2861. If the air be displaced when in a state of covibration, it is not thrown into undulatory circles or waves, like water into which a stone has been cast, but in each of its parts the sonorous figure of the rigid body is repeatedly represented. The vibration of air is a progressive motion of sonorous figures.

2862. If the sonorous figures are not incommensurable, several may be at one and the same time in a single portion of air, without interfering with each other. They harmonize, because they have originated according to concordant laws. But if they are products of different laws, they are then confused, and an indeterminate offensive vibration originates, just as savours become loathsome if they depart from their laws.