Thought and understanding cannot be without subjective contents any more than without an object which suggests individual reflection. Thought is work, and like every other work it requires an object to which it is applied. The statements: I do, I work, I think, must be completed by an answer to the question: What are you doing, working, thinking? Every definite idea, all actual thought, is identical with its content, but not with its object. My desk as a picture in my mind is identical with my idea of it. But my desk outside of my brain is a separate object and distinct from my idea. The idea is to be distinguished from thinking only as a part of the thought process, while the object of my thought exists as a separate entity. We make a distinction between thinking and being. We distinguish between the object of sense perception and its mental image. Nevertheless the intangible idea is also material and real. I perceive my idea of a desk just as plainly as the desk itself. True, if I choose to call only tangible things material, then ideas are not material. But in that case the scent of a rose and the heat of a stove are not material. It would be better to call thoughts sense perceptions. But if it is objected that this would be an incorrect use of the word, because language distinguishes material and mental things, then we dispense with the word material and call thought real. Mind is as real as the tangible table, as the visible light, as the audible sound. While the idea of these things is different from the things themselves, yet it has that in common with them that it is as real as they. Mind is not any more different from a table, a light, a sound, than these things differ among themselves. We do not deny that there is a difference. We merely emphasize that they have the same general nature in common. I hope the reader will not misunderstand me henceforth, when I call the faculty of thought a material quality, a phenomenon of sense perception. Every perception of the senses is based on some object. In order that heat may be real, there must be an object, something else which is heated. The active cannot exist without the passive. The visible cannot exist without the faculty of sight, nor the faculty of sight without visible things. So is the faculty of thought a phenomenon, but it can never exist in itself, it must always be based on some sense perception. Thought appears, like all other phenomena, in connection with an object. The function of the brain is no more a "pure" process than the function of the eye, the scent of a flower, the heat of a stove, or the touch of a table. The fact that a table may be seen, heard, or felt, is due as much to its own nature as to that of another object with which it enters into some relation.