formulate it. Christianity did not invent it; it clarified and defined it, but in principle it is as old as the exercise of human reason. +The basal assumption of thought.+--After making a comprehensive assertion of this kind I suppose I am bound to justify it, and I do not shrink from the task. I say that all thinking starts with an assumption of some kind, and exact thought requires that that assumption shall be the simplest possible, the irreducible minimum beneath which we cannot get. Now when we start thinking about existence as a whole and ourselves in particular, we are compelled to assume the infinite, the finite, and the activity of the former within the latter. In other words we have to postulate God, the universe, and God's operation within the universe. Look at these three conceptions for a moment and it will be seen that every one of them implies the rest; they are a Trinity in unity. The primordial being must be infinite, for there cannot be a finite without something still beyond it. We know, too, that to our experience the universe is finite; we can measure, weigh, and analyse it--an impossible thing to do with an infinite substance. And yet if we think of infinite and finite as two entirely distinct and unrelated modes of existence, we find ourselves in an impossible position, for the infinite must be that outside of which nothing exists or can exist; so of course we are compelled to think of the infinite as ever active within the finite, the source of change and motion, the exhaustless power which makes possible the very idea of development from simplicity to complexity. If the universe were complete in itself, change would not occur, and a cosmic process, evolutionary or otherwise, would be inconceivable. Here, then, we have the basal factors of any true theology, philosophy, or science. Readers of Haeckel's "Riddle of the Universe" will note that that eminent materialist, who professes to do away with the very idea of God, takes these factors for granted; and yet I suppose he would object to being told that he believes in the doctrine of the Trinity. But he does, for he begins by assuming infinite space filled to the farthest with matter ponderable and imponderable, and forthwith proceeds to weigh, measure, and divide the latter as though it were finite! Here are two terms of the doctrine of the Trinity at once. We get the third as soon as Professor Haeckel sets to work to explain the cosmic process, for as he does so he is all the while taking for granted that the infinite is pressing in and up through the finite, evolving beauty and order, light and life.