MEMORY.
105. The memory is defined by Hart ley to be that faculty by which traces of sensations and ideas recur, or are recall ed, in the same order and proportion, ac curately or nearly, in which they were once actually presented.—The rudiments of memory are laid in the perpetual re currency of the same impressions, or groups of impressions. These, by the operations of the retentive power, leave traces or relicts ; and by the operation of the associative power, these are united in the order in which they were presented to the mind. Now, the single sensible impressions and small groups of them be ing few, in comparison of all the large groups, they recur the most frequently, so as sooner to produce the elements of memory.
106. Suppose a person to have so far advanced in life as to have acquired all these elements; that is, that he has ideas of the common appearances and occur rences of life, under a considerable varie ty of subordinate circumstances, which readily recur to his mind by slight causes, he will he thus easily enabled to retrace other occurrences ; for these will consist either of the old impressions variously combined, or of new ones in some way or other connected with them. This may be exemplified and explained by the cir cumstance, that it is difficult to remem ber even well-known words which have no connection with each other ; and still more so words which are neither fami liar, nor formed according to familiar analogies ; but that, on the other hand, persons acquainted with any branch of science or of art, very easily retain facts connected with it which were previously unknown.—The recollection of ideas is also greatly aided by the connection of words, both with them and with the ori ginal impressions ; for words being, from the constant use of language, familiar to persons of moderate mental culture, even in various combinations, they are easily retained, and most materially assist in producing the recurrence of the corres ponding ideas. And thus, when a per son is relating a past fact, the ideas in some cases suggest the words, and in others, the words suggest the ideas.
Hence illiterate persons, other things be ing equal, do not remember nearly so well as others. Hence also the import. ance, contrary to the views of education which a few years ago were so fashion. able, of teaching the young to remember words as well as things ; for in most cases, as words serve as the bond of ideas, ideas will be loose and floating in the mind, unless connected with words.
107. The difference between ideas and sensations principally consists in the great er vividness and distinctness of the lat ter ; but cases are known to occur, in which visual conceptions are so vivid and distinct, that they are mistaken for actual sensations. This is particularly the case when, in consequence of disease, the sys tem is peculiarly susceptible of excite ment; and sometimes when the mind is very much absorbed in contemplating its own ideas, so that the impressions from external Objects produce little effect up on it. It is a fertile source of those ideas respecting apparitions, which are so pre valent among persons of physical sensibi lity, without that culture of the intellect, which would enable them to attend to their own thoughts and manner of think ing. Such lively recollections of past impressions may, however, be usually dis tinguished from sensations, by allowing the attention to relax, so that they may cease to be forcibly detained as objects of consciousness, when it will, in general, be easily perceived that the mind loses sight of them; whereas it can lose sight of impressions from external objects only by fixing the attention upon ideas, or by corporeal motion of some kind or other. —These remarks might perhaps, with greater propriety, have been made under the head of imagination ; because it is sel dom that in such cases the vivid concep tions recur in the exact (or nearly exact) order of actual impression, which is the essential difference between the trains of imagination and those of memory : they are, however, referable to either class of phenomena.