How is this to be understood? If the infinite of the pantheists, by a necessary interior movement, unfolds itself, and becomes multiple, it follows that it is the cause of transient acts. Our mind can attach no other signification to that principle, beyond that of an immanent act, producing transient acts. Now the question arises, Is this ontologically possible? We insist that it is not, and lay down the following proposition: No being, which moves or unfolds itself, that is, which performs transient acts, can do so by its own unaided energy; but requires the aid of another being, different from itself.
An immanent act which produces a transient one does so either by an eternal act, also immanent, and in that case it cannot be the subject of the transient act produced; or it produces a transient act of which it is the subject—so much so that the transient act is its own act, as, for instance, the act by which a sensitive being feels a new sensation, or the act by which an intelligent being begets a thought, are transient acts, the one of the sensitive principle, the other of the rational being. These transient acts modify the subject which produces them, and effect a change in it.
Now, in the first case, if an immanent act which produces transient acts is eternal in duration, these cannot terminate in the subject, by the supposition. For, if the transient act were laid inside the permanent act, it would be its cessation, and in that case the act would no longer be eternal according to the supposition.
In the second place, if an immanent act becomes the subject of transient acts, or, in other words, modifies itself, a sufficient reason must be given, a cause of such modification, by the principle of causality. Why does it modify itself? What is the cause of such a change? The being or subject, or immanent act, does not contain the sufficient cause of the modification or change; because if it contained it, the act produced would be permanent, and not transient, that is, it would have always been in the immanent act. For it is a principle of ontology of immediate evidence that, given the full cause, the effect follows. Now the immanent act in question was before the transient act existed; therefore, the immanent act is not full and sufficient cause of the transient act which modifies it. If it is not the full and sufficient cause of its modification, it cannot modify itself without the aid of exterior being. Now, this exterior being cannot be supposed to be of the same nature with the act in question, otherwise it would itself require aid. Therefore, it must be a being which does it by an eternal immanent act; and that Being is the Infinite of Catholic philosophy.
Apply this demonstration to the second principle of pantheism, that the infinite, by a necessary interior movement, unfolds and develops itself, or modifies itself, it is evident that this second principle, like the first, is ontologically impossible; that the infinite must either be purely, simply, and eternally actual, or it cannot develop itself without the aid of another being of a different nature; consequently that the second pantheistic principle is nothing else but the idea of finite being perfecting itself by the aid of the Infinite of Catholic philosophy.
In order that this conclusion may appear more evident, we subjoin another argument, more adapted to the comprehension of most readers.
According to the pantheistic hypothesis, the infinite, by a necessary interior action, is forced to expand, to develop itself. Now, we want to show that this it cannot do by its unaided energy. We prove it thus: This action of the infinite is a movement; we make use of the word movement in its widest signification, as meaning any action whatever. Now, this movement either existed always in the infinite or it had a beginning. In the system of the pantheists it has a beginning, because they hold that the infinite successively assumes different forms. There was then a time in which it did not move. Then the infinite had only the power, and not the act of moving; and when it did move, it passed from the power to the act.
It will not do for the pantheist to endeavor to avoid this conclusion by saying that the movement of the infinite is eternal. Conceding that the movement is eternal, we ask, is the action only one, or is it multiple? In other words, is the full intensity of its energy concentrated in one movement, or is it divided? The pantheist cannot, in force of his system, admit that the whole intensity of its energy is concentrated in a single movement; otherwise, the successive unfoldings were impossible; the unfolding would be instantaneous, and not successive.
The infinite, then, in its successive unfoldings, passes from the power to the act. Now, it is an ontological principle, as evident as any axiom of Euclid, that no being can pass from the power to the act, from quiet to movement, but by the aid of another being already in act. For power is, in relation to action, as rest is to movement. If the being is in rest, it cannot be in movement; if, on the contrary, it is in movement, it cannot be in rest. Likewise, if the being is supposed to act, it cannot, at the same time, be supposed to be in potentiality. A being in power and action, with regard to the same effects, is as much a contradiction as a being in rest and motion at the same time. To make this more intelligible, let us take an instance. Suppose the seed of a tree, say of a lemon: this seed is in potentiality to become a lemon. But it could never of itself become a lemon; because, if it could, it were already a lemon; it were a lemon, not in power only, but in act. To become a lemon it must be buried in the earth, it must go through the whole process of vegetation, and assimilate to itself whatever it needs from the earth and the air and the sun; and not until then can it be the fruit-tree we call lemon.