2. _Familiarity._--Images and perceptions may come to us, and so may words or other bodily movements, with more or less of the feeling we call “familiarity”. When you recall a tune that you have heard before, either by images or by actually singing it, part of what comes to you may feel familiar, part unfamiliar. This may lead you to judge that you have remembered the familiar part rightly and the unfamiliar part wrongly, but this judgment belongs to a later stage. 3. _Habit-Memory._--We have already discussed this in Chapter VI. People say they remember a poem if they can repeat it correctly. But this does not necessarily involve any recollection of a past occurrence; you may have quite forgotten when and where you read the poem. This sort of memory is mere habit, and is essentially like knowing how to walk although you cannot remember learning to walk. This does not deserve to be called memory in the strict sense. 4. _Recognition._--This has two forms. (_a_) When you see a dog, you can say to yourself “there is a dog”, without recalling any case in which you have seen a dog before, and even without reflecting that there have been such cases. This involves no knowledge about the past; essentially it is only an associative habit. (_b_) You may know “I saw this before”, though you do not know when or where, and cannot recollect the previous occurrence in any way. In such a case there is knowledge about the past, but it is very slight. When you judge: “I saw _this_ before”, the word “this” must be used vaguely, because you did not see exactly what you see now, but only something very like this. Thus all that you are really knowing is that, on some past occasion, you saw something very like what you are seeing now. This is about the minimum of knowledge about the past that actually occurs.