the word as a kind of halo of indefinite import. We have seen that the trend of modern physics is to reject these indefinite attributions and to define its terms according to the way in which we recognise the properties when confronted by them. We recognise the actuality of a particular world because it is that world alone with which consciousness interacts. However much the theoretical physicist may dislike a reference to consciousness, the experimental physicist uses freely this touchstone of actuality. He would perhaps prefer to believe that his instruments and observations are certified as actual by his material sense organs; but the final guarantor is the mind that comes to know the indications of the material organs. Each of us is armed with this touchstone of actuality; by applying it we decide that this sorry world of ours is actual and Utopia is a dream. As our individual consciousnesses are different, so our touchstones are different; but fortunately they all agree in their indication of actuality—or at any rate those which agree are in sufficient majority to shut the others up in lunatic asylums. It is natural that theoretical physics in its formulation of a general scheme of law should leave out of account actuality and the guarantor of actuality. For it is just this omission which makes the difference between a law of Nature and a particular sequence of events. That which is possible (or not “too improbable”) is the domain of natural science; that which is actual is the domain of natural history. We need scarcely add that the contemplation in natural science of a wider domain than [Pg 267] the actual leads to a far better understanding of the actual. From a broader point of view than that of elaborating the physical scheme of law we cannot treat the connection with mind as merely an incident in a self-existent inorganic world. In saying that the differentiation of the actual from the non-actual is only expressible by reference to mind I do not mean to imply that a universe without conscious mind would have no more status than Utopia. But its property of actuality would be indefinable since the one approach to a definition is cut off. The actuality of Nature is like the beauty of Nature. We can scarcely describe the beauty of a landscape as non-existent when there is no conscious being to witness it; but it is through consciousness that we can attribute a meaning to it. And so it is with the actuality of the world. If actuality means “known to mind” then it is a purely subjective character of the world; to make it objective we must substitute “knowable to mind”. The less stress we lay on the accident of parts of the world being known at the present era to particular minds, the more stress we must lay on the potentiality of being known to mind as a fundamental objective property of matter, giving it the status of actuality whether individual consciousness is taking note of it or not.