Eternity is duration without succession or change; duratio tota simul, as the schoolmen would say. Hence it excludes the idea either of beginning or end. But duration and actuality are one and the same thing. Therefore actuality itself is duration itself; that is to say, duration without succession or change.
Now, God is actuality itself. Therefore he is eternal.
III.
God Is Immutable.
Immutability is life without succession or change; or, in other words, life without beginning or end, and without being subject to modifications. Now life is action. Action then, without succession or change, is immutability.
God is action itself. Therefore God is immutable.
IV.
God Is Infinite.
Infinity is being itself with the exclusion of limits, that is, of not being; or, to express ourselves more intelligibly, it is being or perfection in its utmost and supremest actuality, excluding the possibility of any successive actualization, for the reason of its being already all possible actualization. Human language is so imperfect and so inadequate that, even in our efforts to avoid in the definition of the infinite all idea of succession or development, we are forced to make use of words which seem to suppose it. Those who are trained to think logically will grasp the idea without much effort; for the words being itself, to the exclusion of not being or limitation, sufficiently and adequately define the infinite. Now, God, as action itself, is being itself. Therefore, God is infinite.
V.
Immensity Is The Presence Of The
Whole Being Of God In His Actions.
This definition of immensity, being somewhat different in words from that commonly given by metaphysicians, requires explanation. Let the reader, then, pay particular attention to the following remarks.