The following is an illustrative example of another kind. Liebig (_Chemie in Anwendung auf Agrikultur_, p. 501), says: “If we bring moist copper into air which contains carbonic acid, the affinity of the metal for the oxygen of the air will be increased by the contact with this acid to such a degree that the two will combine with each other; its surface will be coated with green carbonic oxide of copper. But now two bodies which have the capacity of combining, the moment they meet assume opposite electrical conditions. Therefore if we touch the copper with iron, by producing a special electrical state, the capacity of the copper to enter into combination with the oxygen is destroyed; even under the above conditions it remains bright.” The fact is well known and of technical use. I quote it in order to say that here the will of the copper, laid claim to and occupied by the electrical opposition to iron, leaves unused the opportunity which presents itself for its chemical affinity for oxygen and carbonic acid. Accordingly it conducts itself exactly as the will in a man who omits an action which he would otherwise feel himself moved to in order to perform another to which a stronger motive urges him. I have shown in the first volume that the forces of nature lie outside the chain of causes and effects, because they constitute their accompanying condition, their metaphysical foundation, and therefore prove themselves to be eternal and omnipresent, _i.e._, independent of time and space. Even in the uncontested truth that what is essential to a _cause_ as such consists in this, that it will produce the same effect at any future time as it does now, it is already involved that something lies in the cause which is independent of the course of time, _i.e._, is outside of all time; this is the force of nature which manifests itself in it. One can even convince oneself to a certain extent empirically and as a matter of fact of the _ideality_ of this form of our perception by fixing one’s eyes upon the powerlessness of time as opposed to natural forces. If, for example, a rotatory motion is imparted to a planet by some external cause, if no new cause enters to stop it, this motion will endure for ever. This could not be so if time were something in itself and had an objective, real existence; for then it would necessarily also produce some effect. Thus we see here, on the one hand, the _forces of nature_, which manifest themselves in that rotation, and, if it is once begun, carry it on for ever without becoming weary or dying out, prove themselves to be eternal or timeless, and consequently absolutely real and existing in themselves; and, on the other hand, _time_ as something which consists only in the manner in which we apprehend that phenomenon, since it exerts no power and no influence upon the phenomenon itself; for _what does not act is not_.