On the other hand, one who has cultivated the art of reading will instantly discern, in a book or journal or pamphlet, what ought to be remembered because it meets one's personal needs or is of value as general knowledge. What he thus learns is incorporated in his mental analogue of this or that problem or thing, further correcting the mental picture or enlarging it so that it becomes more exact and precise. Should some practical problem suddenly demand examination or solution, memory will immediately select the opportune information from the mass that has been acquired through years of reading and will place this information at the service of one's powers of judgment so as to get a new and clearer view of the problem in question or produce a definitive solution.