Let us look a little more closely at what is implied by change. It means that the being which is subject to it is never at any moment the whole of itself: it possesses its being successively, as the philosophers say. You, for instance, are never at any moment the whole of yourself. What you were last year, what you will be next year, all belongs to the totality called you. But last year has gone, and next year has not arrived. It is obviously an overwhelming limitation that one never wholly possesses one’s self, that one possesses one’s being in successive moments and not simply in one act of being, that one is never wholly there. There is no such limitation in God. He possesses Himself wholly in one act of being. This is what we call His eternity. Thus eternity does’ not mean time open at both ends, time stretching away back into the past with no beginning, stretching away forward into the future with no ending. In fact we are back at our earlier principle: that infinity means not only the absence of external limits, but of internal divisions as well. Just as space has parts lying alongside one another, time has parts following one another. The Infinite has no parts, of either (or any other conceivable) sort. Eternity is not time, however much we may try to glorify the concept of time. The philosophic definition of eternity is in two Latin words, tota simul,1 which may be roughly translated as “all at once”. God’s eternity means that He possesses the totality of what He is, not in successive acts as we do, but in one single act.
Bernard Shaw phrased the experience very admirably: “When we learn something, it feels at first as if we have lost something.” It is so, for instance, with a new stroke at tennis. Our old stroke had been a pretty incompetent affair, of the sort to make a professional laugh. But it had been ours, we were used to it, all our muscles were in the habit of it. The new stroke is doubtless better, but we are not in the way of it, we cannot do anything with it, and all the joy goes out of tennis—but only until we have mastered the new way. Then, quite suddenly, we find that the whole game is a new experience.