5. _Immediate Memory._--I come now to a region intermediate between sensation and true memory, the region of what is sometimes called “immediate memory”. When a sense-organ is stimulated, it does not, on the cessation of the stimulus, return at once to its unstimulated condition: it goes on (so to speak) vibrating, like a piano-string, for a short time. For example, when you see a flash of lightning, your sensation, brief as it is, lasts much longer than the lightning as a physical occurrence. There is a period during which a sensation is fading: it is then called an “acoleuthic” sensation. It is owing to this fact that you can see a movement as a whole. As observed before, you cannot see the minute-hand of a watch moving, but you can see the second-hand moving. That is because it is in several appreciably different places within the short time that is required for one visual sensation to fade, so that you do actually, at one moment, see it in several places. The fading sensations, however, feel different from those that are fresh, and thus the various positions which are all sensibly present are placed in a series by the degree of fading, and you acquire the perception of movement as a process. Exactly the same considerations apply to hearing a spoken sentence. Thus not only an instant, but a short finite time is sensibly present to you at any moment. This short finite time is called the “specious present”. By the felt degree of fading, you can distinguish earlier and later in the specious present, and thus experience temporal succession without the need of true memory. If you see me quickly move my arm from left to right, you have an experience which is quite different from what you would have if you now saw it at the right and remembered that a little while ago you saw it at the left. The difference is that, in the quick movement, the whole falls within the specious present, so that the entire process is sensible. The knowledge of something as in the immediate past, though still sensible, is called “immediate memory”. It has great importance in connection with our apprehension of temporal processes, but cannot count as a form of true memory. 6. _True Recollection._--We will suppose, for the sake of definiteness, that I am remembering what I had for breakfast this morning. There are two questions which we must ask about this occurrence: (_a_) What is happening now when I recollect? (_b_) What is the relation of the present happening to the event remembered? As to what is happening now, my recollection may involve either images or words; in the latter case, the words themselves may be merely imagined. I will take the case in which there are images without words, which must be the more primitive, since we cannot suppose that memory would be impossible without words.