FINITE BEING.
89. Uncreated Being is that which exists of itself; created being, that which holds its being from another. -- Uncreated Being is none else than God, who gives being to everything and receives it from none; He is Being by essence, whereas the others are being by participation. He is also called Necessary Being, because He cannot but exist, while creatures are called contingent beings, because their non-existence is possible.
90. Uncreated Being is actually infinite, that is, it is bounded by no limit. -- The infinite is of two kinds: the actual infinite, which really and indeed is bounded by no limit, and the potential infinite or the indefinite, which is only the finite to which something can always he added. God alone is actually infinite. In creatures there is only potential infinity. For they cannot be actually infinite in perfection of being, since they have being only by participation; moreover, it is possible for them not to exist, and this implies a great imperfection in their essence. No creature can be actually infinite in magnitude, because no property of a finite substance can be infinite. Neither can there be an actually infinite number, because a multitude that can ever be increased is not infinite; but however great the multitude be supposed, it can always be increased. Lastly, no creature can be infinite in the intensity of any of its qualities, because it is impossible for a finite subject to contain an infinitely perfect quality.
91. There is a potential infinity in creatures. -- No quantity is so great that it cannot be further increased; no creature has all perfections, since it is essentially contingent.
92. Material entities have a limit to their smallness, living beings have also a limit to their largeness. -- A natural form requires a certain quantity in the matter which it determines. A quantity may be so small that a smaller one would not suffice for the operations of any form whatever; therefore such a quantity cannot be informed, or determined by form. With regard to living beings, experience shows that they have certain limits as to maximum and minimum size.{1}
{1} See also Metaphysics of the School, vol. iii., pp. 307, 314-316.