The memory has no enemy greater than lack of concentration. The ability to concentrate is important in every effort of memory. For instance, if, while you are reading a book on travel in the United States, you begin to think of trips you have made to Europe, you will remember little of what you read.

The term "concentration" has become rather hackneyed through constant loose usage, and it has a more exact meaning than is commonly given it. Many people believe they are "concentrating" to a sufficient degree when they succeed in doing their jobs competently even when surrounded by distracting noises. That this is not true concentration is evident when one attempts any sort of reasonably simple experiment demanding real, authentic concentration.

As exercises in concentration I recommend the following:

Stretch out in a comfortable position on a couch or bed and be careful to relax your whole body, with no strain or tension anywhere. Close your eyes and try to visualize the form of some simple, familiar article. As soon as you succeed in doing so, concentrate your thoughts on this article to the exclusion of everything else and do not let them stray in any direction if you can help it.

Suppose, for example, you choose an electric light bulb. You must keep your mind on the bulb and not let it stray to the chandelier or the room it illuminates or the people in the room.

At first it will be difficult for you to sustain this experiment for longer than four or five seconds. But by gradual, regular drill, you will succeed in running the time of concentration up to ten seconds or longer. When you have learned to do this, make the experiment more difficult. Instead of the quiet room, select a more or less populous spot where you are unable to stretch out in a position conducive to concentration, and where, moreover, the impressions on eye and ear will make it more difficult for you to collect your thoughts.

2. A more difficult, and consequently more interesting, exercise in concentration consists in remembering as exactly as possible the occurrences of the hour immediately preceding this. It is not sufficient for you to recall only that you were on Broadway where you bought a book or had an ice-cream soda. The correct method of carrying out the experiment would be somewhat as follows:

"It is now eight o'clock. At seven I left my office on Forty-second Street and went to the subway station at Times Square. On the way the show window of X's store caught my eye because it contained a particularly good-looking suit..."

If you carry out the exercise in this manner, you will make an important experiment in concentration: the more detailed, the better. That is, the more particulars you can recall, the more value the exercise will have for you. Of course, it is impossible for you to remember all the people you saw in the subway or all the thoughts that passed through your mind during the ride. But you will find that diligent, patient practice will increase your abilities.

It is important to remember that, aside from increasing your ability to concentrate, this exercise will in time make it possible for you to remember with a considerable degree of accuracy conversations which you have held and sensations which you have experienced. It is hardly necessary to point out how useful this can be in daily life.

If you practice these two simple exercises, you powers of concentration should increase greatly.