4. Teach the subject to or discuss it with a fellow student. By this you vitalize the memories you have, you link them firmly together, you lend to them the ardor of usefulness and of victory. You are forced to realize where the gaps, the lacunae of your knowledge come, and are made to fill them in. Thus the best way to remember a fact is to find a use for it and to link it to your interests and your purposes. Unrelated it has no value; related it becomes in fact a part of you. After that the mechanics of memory necessitate the making of as many pathways to that fact as possible, and this means deliberately to associate the fact by sound, by speech and by action. The advertised schemes of memory training are simply association schemes, old as the hills, and having value indeed, but too much is claimed for them. A splendid memory is born, not made; but any memory, except where disease has entered, can be improved by training. It is because lectures on the whole do not supply enough associations or arouse enough interest that the lecture is the poorest method of teaching or learning. Man's mind sticks easily to things, but with difficulty to words about things. To maintain attention for an hour or so, while sitting, is a task, and there develops a tendency either to a hypnoidal state in which the mind follows uncritically, or to a restless uneasiness with wandering mind and fatigue of body. A demonstration, on the other hand, a laboratory experiment with short, personal instruction, a bodily contact with the problem calls into play interest, enthusiasm, curiosity, motor images, the use of the hands, and is THE method of teaching. There are at present excellent psychological methods of testing out the memory capacity. Every one engaged in any responsible work, or troubled about his memory, should be so tested. While there are other qualities of mind of great importance, memory is basic, and no one can really understand himself who is in doubt about his memory. In such diseases as neurasthenia one of the commonest complaints is the "loss of memory," which greatly troubles the patient. As a matter of fact, what is impaired is interest and attention, and when the patient realizes this he is usually quite relieved. The man who has a poor memory may become very successful if he develops systems of recording, filing, indexing, but his possibilities of knowledge are greatly reduced by his defect.[1] [1] It is the growth of the subject matter of knowledge that makes necessary the elaborate systems of indexing, etc., now so important. It is as much as man can do to follow the places where the men work, let alone what they are doing. This growth of knowledge is getting to be an extra-human phenomenon. Of this Graham Wallas has written entertainingly.