It can easily be proved that absolutely independent existence cannot be attributed to two beings. For, if that were the case, absolutely independent existence would be a property added to the substance of both; neither of them would be absolutely independent on account of their essence, but only through a certain property, viz., that of this independent existence, which is common to both. It can besides be shown in many ways that independent existence cannot be reconciled with the principle of dualism by any means. It would make no difference, whether we imagine two beings of similar or of different properties. The reason for all this is to be sought in the absolute simplicity and in the utmost perfection of the essence of this being, which is the only member of its species, and does not depend on any cause whatever; this being has therefore nothing in common with other beings. Fourth Argument.—This is likewise a well-known philosophical argument. We constantly see things passing from a state of potentiality to that of actuality, but in every such case there is for that transition of a thing an agent separate from it (Prop. XVIII.). It is likewise clear that the agent has also passed from potentiality to actuality. It has at first been potential, because it could not be actual, owing to some obstacle contained in itself, or on account of the absence of a certain relation between itself and the object of its action; it became an actual agent as soon as that relation was present. Whichever cause be assumed, an agent is again necessary to remove the obstacle or to create the relation. The same can be argued respecting this last-mentioned agent that creates the relation or removes the obstacle. This series of causes cannot go on ad infinitum; we must at last arrive at a cause of the transition of an object from the state of potentiality to that of actuality, which is constant, and admits of no potentiality whatever. In the essence of this cause nothing exists potentially, for if its essence included any possibility of existence it would not exist at all (Prop. XXIII.); it cannot be corporeal, but it must be spiritual (Prop. XXIV.); and the immaterial being that includes no possibility whatever, but exists actually by its own essence, is God. Since He is incorporeal, as has been demonstrated, it follows that He is One (Prop. XVI.). Even if we were to admit the Eternity of the Universe, we could by any of these methods prove the existence of God; that He is One and incorporeal, and that He does not reside as a force in a corporeal object.