force is exactly of the same stimulated and not transferred nature, then, surely, a great advantage will have been thus gained toward a correct understanding of natural phenomena and their relation to each other.
It would then be clearly perceived that Nature does not consist of so many particles of inert matter, held together or pushed about by a set of mysterious agents; but that it rather consists in the disturbance, the overthrow, and the new formation, of equilibrated states of energies.
I have found myself reluctantly compelled to advance this general statement, in order to fulfill the obligations undertaken in this section. For, how am I to establish the gradual, unbroken development of the organic world from inorganic beginnings, when already in the domain of inorganic activity there are believed to exist so many different modes of force, so many kinds of self-sustained and transferable agents? It is true, the so-called forces, the specific motive activities, by diving into certain substances, are said to be in some unknown way "transformed "or" converted "into each other: so much friction into so much heat, or so much electricity. In this conception the identity of a supposed agent or force is evidently sustained in thought. Struck by the definite proportionality found to obtain between the changes occurring simultaneously in the substratum from which the force is thought to have been transferred, and the substratum to which it is thought to have been transferred, the mind is induced by means of a fictitious entity substantially to connect the changes as such, losing sight of the true substances, of which the changes are in reality mere affections. However much the notion may be formally repudiated, the forces are nevertheless in science still conceived as specific entities; to which the current expressions "correlation of forces, "equivalence of forces," "transmutation of forces," etc., bear sufficient witness.
If friction can become electric force, why cannot heat become vital force? And this is exactly what is generally maintained. If it be the rubbing that is or makes the electricity in the sealing-wax, then, surely, it must be the heat that is or makes the vitality in the hen's egg. This also, but somewhat more reservedly, is at times advanced. So much mechanical force converted into so much electric force, in the former instance, whereby—as easily perceived—the preëstablished specific molecular constitution of the sealing-wax is counted for nothing: so much heat converted into so much vital force, in the latter instance, whereby the preëstablished most specific molecular affinities within the egg-substance are counted for nothing. Is not even the proportionality between the changes entirely limited and quantitatively determined by the nature and state of the manifesting substances?
Whether the forces be conceived as specific entities, as definite modes of motion, or as different affections of matter, the idea of their equivalence and convertibility is just as unwarranted, though not so palpably incongruous, as the idea of the equivalence and convertibility of air-
