In this connection we should remember that attention depends largely upon interest. Therefore we would naturally expect to find that we remember interesting things far more readily than those which lack interest. This supposition is borne out in actual experience. This accounts for the fact that every one remembers a certain class of things better than he does others. One remembers faces, another dates, another spoken conversation, another written words, and so on. It will be found, as a rule, that each person is interested in the class of things which he most easily remembers. The artist easily remembers faces and details of faces, or scenery and details thereof. The musician easily recalls passages or bars of music, often of a most complicated nature. The speculator easily recalls the quotations of his favorite stocks. The racing man recalls without difficulty the "odds" posted on a certain horse on a certain day, or the details of a race which was run many years ago. The moral is: _Arouse and induce an interest in the things which you wish to remember_. This interest may be aroused by studying the things in question, as we have suggested in a preceding chapter. VISUALIZATION IN MEMORY. Many of the best authorities hold that original impressions may be made clear and deep, and the process of reproduction accordingly rendered more efficient, by the practice of _visualizing_ the thing to be remembered. By visualizing is meant the formation of a _mental image_ of the thing in the imagination. If you wish to remember the appearance of anything, look at it closely, with attention, and then turning away from it endeavor to reproduce its appearance as a mental picture in the mind. If this is done, a particularly clear impression will be made in the memory, and when you recall the thing you will find that you will also recall the clear mental image of it. Of course the greater the number of details observed and included in the original mental image, the greater the remembered detail. PERCEPTION IN MEMORY. Not only is attention necessary in forming clear memory records, but careful perception is also important. Without clear perception there is a lack of detail in the retained record, and the element of association is lacking. It is not enough to merely remember the thing itself; we should also remember _what_ it is, and all about it. The practice of the methods of developing perception, given in a preceding lesson, will tend to develop and train the retentive, reproductive, recognitive, and locative powers of the memory. The rule is: _The greater the degree of perception accorded a thing, the greater the detail of the retained impression, and the greater the ease of the recollection_. UNDERSTANDING AND MEMORY.