We must now return to the subject of memory. Memory proper does not, like imagination, involve a re-arrangement of elements derived from past experience; on the contrary, it should restore such elements in the pattern in which they occurred. This is the vital difference between memory and imagination; belief, even belief involving reference to the past, may, as we have seen, be present in what is really imagination though it may not seem to be so to the person concerned. That being so, we still have to consider what constitutes the reference to the past, since the view tentatively suggested before we had considered imagination turns out to be inadequate. There is one possible view, suggested, though not definitely adopted, by Dr. Broad in his chapter on “Memory” already referred to. According to this view, we have to start from temporal succession as perceived within what is called the “specious present”, _i.e._ a short period of time such that the events that occur throughout it can be perceived together. (I shall return to this subject presently.) For example, you can see a quick movement as a whole; you are not merely aware that the object was first in one place and then in another. You can see the movement of the second-hand of a watch, but not of the hour-hand or minute-hand. When you see a movement in this sense, you are aware that one part of it is earlier than another. Thus you acquire the idea “earlier”, and you can mean by “past” “earlier than this”, where “this” is what is actually happening. This is a logically possible theory, but it seems nevertheless somewhat difficult to believe. I do not know, however, of any easier theory, and I shall therefore adopt it provisionally while waiting for something better. For the understanding of memory, it is a help to consider the links connecting its most developed forms with other occurrences of a less complex kind. True recollection comes at the end of a series of stages. I shall distinguish five stages on the way, so that recollection becomes the sixth in gradual progress. The stages are as follows: 1. _Images._--As we have seen, images, at any rate in their simpler parts, in fact copy past sensations more or less vaguely, even when they are not known to do so. Images are “mnemic” phenomena, in the sense that they are called up by stimuli formerly associated with their prototypes, so that their occurrence is a result of past experience according to the law of association. But obviously an image which in fact copies a past occurrence does not constitute a recollection unless it is _felt_ to be a copy.