Being means that we recognize its possession of far more validity than, in our private capacity, we shall ever test. It is thus with common sense, much as it was with mathematics. The mathematician finds his way in the eternal world by means of experiments upon the transient facts of his inner and ideal experience of this instant’s contents. The student of science or the plain man of everyday life believes himself to be dealing with a realm of validity far transcending his personal experience. But his only means of testing any concrete assertion about that world comes to him through the very fragmentary observation of what happens in his inner life from instant to instant.
To generalize, then, the problem so far furnished us by our Third Conception of Reality, we find this as our situation. Ask me how I discover, in a concrete case, the validity of my idea, how I make it out for certain that a given experience is possible; and then I have to answer, “By actual experience alone.” When I say then, “A given idea is certainly valid,” I primarily mean merely, “A given idea is fulfilled in actual present experience.” But if you ask me what I regard as the range of the realm of validity, and what I think to be the extent of possible experience, and of the truth of ideas, then I can only say that the range of valid possible experience is viewed by me as infinitely more extended than my actual human experience. From the mathematical point of view the realm of truth is in fact explicitly infinite. From the point of view of natural science and of common sense, the world of valid possible experience is not only far wider than
