of the other. In proportion as this ensues, the mind's interest in passing events is likely to fail, for what is no longer clearly apprehended no longer awakens the same interest and attention as formerly. This directly affects the vividness of conception, and indirectly also reacts upon the frequency of coëxistence, for what we do not clearly apprehend, nor feel much interest in, will not be likely often to recur to mind, nor shall we dwell upon it when presented. There is thus brought about, by the mutual action and reaction of the causes now specified, a failure more or less complete of the essential conditions of a retentive memory.
The old man dwells accordingly much in the past. His life is behind him, and not in advance. He is unobservant of passing events, because he neither clearly apprehends them, now that his connection with the outer world is in a measure interrupted by the decay of sense, nor does he much care about them, for the same reason. His attention and interest, withdrawn in a manner from these, revert to the past. Those things he remembers, the sports and companions of his youth, and the stirring events of his best and most active years, for those things have been frequently associated in his mind, linked with each other, and with all the past of his life, and they have deeply interested him. Hence they are remembered while yesterday is forgotten.
Varieties of Memory.—Why is it, you ask, that memory seems to select for itself now one and now another field of operation, one man remembering dates, another events or facts in history, another words or pages of a book, while in each case the memory of other things, of every thing that lies beyond or without the favorite range of topics, is defective? Manifestly for much the same reason already given. The mind has its favorite subjects of investigation and thought; to these it frequently recurs, and dwells on them with interest; there is, consequently, frequency of coëxistence, and vividness of conception—the very conditions of retentiveness—while, at the same time, the mind being preöccupied with the given subjects, and the attention and interest withdrawn from other things, the memory of other things is proportionably deficient. We remember, in other words, just those things best, in which we are most interested, and with which we have most to do.
This explains why we forget names so readily. We have more to do with, and are more interested in, persons, than their names; the latter we have occasion to think of much less often than the former. The sign occurs less frequently than the thing signified.
V. Cultivation of Memory.
The principles already advanced furnish a clue to the proper and successful cultivation of the memory. Like all other powers, this may be cultivated, and to a wonderful degree; and, like all other powers, it gains strength by use, by exercise. The first and chief direction, then, if you would cultivate and strengthen this faculty of the mind, is, exercise it; train it to do its work—to do it quickly, easily, accurately, and well—as you train yourself to handle the keys of an instrument, or to add up a column of figures with promptness and accuracy.
To be more specific.—As regards any particular thing which you wish to remember: 1. Grasp it fully, clearly, definitely in the mind; be sure you have it exactly—it, and not something like it or something about it. 2. Connect it with other things that are known; suffer it to link itself with other ideas and impressions already in the mind, that you may have something to recall it by. 3. Frequently revert to it, until you are sure that it has become a permanent possession, and one which you can at any time recall by any one of numerous connecting links. In this way you secure the two conditions already specified as essential, viz., frequency of coëxistence, and vividness of conception.
Systems of artificial Memory.—A thing is recalled by the suggestion of any coëxisting thought or feeling. Observing this, ingenious men have availed themselves of the principle of association to construct various mechanical or artificial systems of memory, usually termed mnemonics. The principle of the construction is this: should you see an elm or an oak-tree, or hear a particular tune whistled, at the same time that you were going through a demonstration in Euclid, you would be likely to think of the tree or the tune whenever next you had occasion to repeat that demonstration. The sight of the diagram would recall the associated object. They stand together in your mind afterward. This we have already found to be the groundwork and chief element of all association of ideas and feelings, viz., prior coëxistence in the mind. Suppose, now, you wish to fix in the mind the list of English kings. Make out a corresponding list of simple figures, or images of objects, giving each its invariable place in relation to the series: No. 1. a pump; No. 2. a goose, etc., till you reach a sufficient number, say a hundred. These are committed to memory, fixed indelibly in the mind. You then associate with those figures your English kings; Charles I. stands by the pump; Charles II. pursues the goose; James hugs the bear, and so on. These things thus once firmly linked together, remain afterward associated, and the figure serves at once to recall the associate monarch and to fix his place in the series. The same series of figures, of course, will serve for any number of different series of events, personages, etc., which are to be remembered.
Utility questioned.—It may be seriously questioned, I think, whether such systems are of real value; whether they do not really weaken the memory and throw it into disuse, by departing from the ordinary laws and methods of suggestion, and substituting a purely artificial, arbitrary and mechanical process; whether, moreover, they really accomplish what they propose; whether, since the signs or figures have no natural relation to each other, and none to the things signified, but only the arbitrary relation imposed by the system, it is not really as difficult to fix the connection of the two things in your mind, e. g., to remember that Charles the Second is represented by a dog or by a goose, as it would be simply, and in the natural way, to remember the things themselves without any such association.
Extent to which the Memory may be cultivated.—The extent to which the cultivation of the memory may be carried by due training and care, is a topic worthy of some attention. Men of reflection and thought, and generally men of studious habits, literary men and authors, do not, for the most part, rely so much upon the memory as men of a more practical cast and of business pursuits; for this reason, viz., the want of due exercise, this faculty of their minds is not in the most favorable circumstances for development. Some striking exceptions, however, we shall have occasion presently to mention.
It has been already remarked, that prior to the art of printing, the cultivation of the memory was an object of far greater importance, to those who were destined for public life, than it is in modern times, and consequently instances of remarkable memory are much more frequently to be met with among the ancients than among the men of our times. The same remark will apply to men of different pursuits in any age: the more one has occasion to employ the memory, the more striking will be its development.
Instances of extraordinary Memory.—Cyrus, it is said, knew the name of every officer, Pliny has it of every soldier, that served under him. Themistocles could call by name each one of the twenty thousand citizens of Athens. Hortensius could sit all day at an auction, and at evening give an account from memory of every thing sold, the purchaser, and the price. Muretus saw at Padua a young Corsican, says Mr. Stewart, who could repeat, without hesitation, thirty-six thousand names in the order in which he heard them, and then reverse the order and proceed backward to the first.
Dr. Wallis of Oxford, on one occasion, at night, in bed, proposed to himself a number of fifty-three places, and found its square root to twenty-seven places, and, without writing down numbers at all, dictated the result from memory twenty days afterward. It was not unusual with him to perform arithmetical operations in the dark, as the extraction of roots, e. g., to forty decimal places. The distinguished Euler, blind from early life, had always in his memory a table of the first six powers of all numbers, from one to one hundred. On one occasion two of his pupils, calculating a converging series, on reaching the seventeenth term, found their results differing by one unit at the fiftieth figure, and in order to decide which was correct, Euler went over the whole in his head, and his decision was found afterward to be correct. Pascal forgot nothing of what he
