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 His attention and interest, withdrawn in a manner from these, revert to the past.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at the same time, the mind being preöccupied with the given subjects, and the attention and interest withdrawn from other things, the memory of other things is proportionably deficient.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.