A very important factor in connection with memory is the matter of meaning. If a person will try to memorize a list of nonsense words, he will find that it is much more difficult than to memorize words that have meaning. This is a significant fact. It means that as material approaches nonsense, it is difficult to memorize. Therefore we should always try to grasp the meaning of a thing, its significance. In science, let us always ask, what is the meaning of this fact? What bearing does it have on other facts? How does it affect the meaning of other facts? =Kinds of Memories.= We should not speak of memory as if it were some sort of power like muscular strength. We should always speak of _memories_. Memories may be classified from several different points of view: A classification may be based on the kind of material, as memory for concrete things, the actual objects of experience, on the one hand, and memory for abstract material, such as names of things, their attributes and relations, on the other. Again, we can base a classification on the type of ideation to which the material appeals, as auditory memory, visual memory, motor memory. We can also base a classification on the principle of _meaning_. This principle of classification would give us at least three classes: memory for ideas as expressed in sentences, logical memory; memory for series of meaningful words not logically related in sentences, rote memory; memory for series of meaningless words, a form of rote memory. This classification is not meant to be complete, but only suggestive. With every change in the kind of material, the method of presenting the material to the subject, or the manner in which the subject deals with the material, there may be a change in the effectiveness of memory. While these different kinds or aspects of memory may have some relation to one another, they are to some extent independent. One may have a good rote memory and a poor logical memory, or a poor rote memory and a good logical memory. That is to say, one may be very poor at remembering the exact words of a book, but be good at remembering the meaning, the ideas, of the book. One may be good at organizing meaningful material but poor at remembering mere words. On the other hand, these conditions may be reversed; one may remember the words but never get the meaning. It is of course possible that much of this difference is due to habit and experience, but some of the difference is beyond doubt due to original differences in the nervous system and brain. These differences should be determined in the case of all children. It is quite a common thing to find a feeble-minded person with a good rote memory, but such a person never has a good logical memory. One can have a good rote memory without understanding, one cannot have a good logical memory without understanding.