It is a mistake, therefore, to speak about an “eternal unchangeable underlying substance” as I am afraid I did in the last pages of _Luck or Cunning_? but I am not going to be at the trouble of seeing. For, if the substance is eternal and unknowable and unchangeable, it is tantamount to nothing. Nothing can be nearer non-existence than eternal unknowableness and unchangeableness. If, on the other hand, the substance changes, then it is not unknowable, or uncognisable, for by cognising its changes we cognise it. Changes are the only things that we can cognise. Besides, we cannot have substance changing without condition changing, and if we could we might as well ignore condition. Does it not seem as though, since the motions or states are all that we cognise, they should be all that we need take account of? Change of condition is change of substance. Then what do we want with substance? Why have two ideas when one will do? I suppose it has all come about because there are so many tables and chairs and stones that appear not to be moving, and this gave us the idea of a solid substance without any motion in it. How would it be to start with motion approximately patent, and motion approximately latent (absolute patency and absolute latency being unattainable), and lay down that motion latent as motion becomes patent as substance, or matter of chair-and-table order; and that when patent as motion it is latent as matter and substance? I am only just recovering from severe influenza and have no doubt I have been writing nonsense. Matter and Mind i People say we can conceive the existence of matter and the existence of mind. I doubt it. I doubt how far we have any definite conception of mind or of matter, pure and simple. What is meant by conceiving a thing or understanding it? When we hear of a piece of matter instinct with mind, as protoplasm, for example, there certainly comes up before our closed eyes an idea, a picture which we imagine to bear some resemblance to the thing we are hearing of. But when we try to think of matter apart from every attribute of matter (and this I suspect comes ultimately to “apart from every attribute of mind”) we get no image before our closed eyes—we realise nothing to ourselves. Perhaps we surreptitiously introduce some little attribute, and then we think we have conceived of matter pure and simple, but this I think is as far as we can go. The like holds good for mind: we must smuggle in a little matter before we get any definite idea at all. ii Matter and mind are as heat and cold, as life and death, certainty and uncertainty, union and separateness. There is no absolute heat, life, certainty, union, nor is there any absolute cold, death, uncertainty or separateness.