It is undeniable that this characteristic of being directed to objects is, in some sense, a property of cognition and conation, but there is room for great difference of opinion as to the proper analysis of the property. I think we cannot hope to understand the word “mental” until we have undertaken this analysis, and I shall therefore proceed to address myself to it. I shall confine myself to cognition, which is more important for our present purposes than conation. As regards cognition, though philosophers have disagreed widely, I think that, until recently, most would have assented to at least the following paragraph: Cognition is of various sorts. Take, as important kinds, perception, memory, conception, and beliefs involving concepts. Perception is the ordinary awareness of sensible objects: seeing a table, hearing a piano, and so on. Memory is awareness of a past occurrence, when this awareness is direct, not inferred or derived from testimony. Conception is more difficult to characterise. One may say, as a way of pointing out what is intended, that we “conceive” whenever we understand the meaning of an abstract word, or think of that which is in fact the meaning of the word. If you see a white patch of snow, or recall it by means of images, you do not have a concept; but if you think about whiteness, you have a concept. Similarly if, after seeing a number of coins, you think about roundness as a common characteristic of all of them, you have a concept. The object of your thought, in such a case, is a _universal_ or a Platonic idea. Every sentence must contain at least one word expressing a concept, and therefore every belief that can be expressed in words contains concepts. Each of these kinds of cognitive attitude involves its own problems. In the present chapter we are concerned with perception. This has to be treated both introspectively and causally; it is the introspective treatment that we have now to undertake. When you have the experience called “seeing a table”, there is a certain amount of difference between your unreflecting judgment and what careful examination reveals as to the nature of your experience. You judge that the table is rectangular, but the patch of colour in your visual field is not a rectangle; when you learn to draw, you have to draw the table as it really seems and not as it seems to seem. You have images of sensations of touch; if you were to try to touch the table and it turned out to be an optical illusion, you would get a violent shock of surprise. You have also expectations of a certain degree of permanence and weight. If you went to lift the table, you would find your muscles quite wrongly adjusted if the table were much lighter than it looked. All these elements must be included in the perception, though not in the sensation.