in every branch of knowledge after the most mature consideration, and the result of it established.  Such a selection must be based on a sifting of matters which are necessary and important for a man to know in general, and also for him to know in a particular profession or calling.  Knowledge of the first kind would have to be divided into graduated courses, like an encyclopaedia, corresponding to the degree of general culture which each man has attained in his external circumstances; from a course restricted to what is necessary for primary instruction up to the matter contained in every branch of the philosophical faculty.  Knowledge of the second kind would, however, be reserved for him who had really mastered the selection in all its branches.  The whole would give a canon specially devised for intellectual education, which naturally would require revision every ten years.  By such an arrangement the youthful power of the memory would be put to the best advantage, and it would furnish the faculty of judgment with excellent material when it appeared later on.

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What is meant by maturity of knowledge is that state of perfection to which any one individual is able to bring it, when an exact correspondence has been effected between the whole of his abstract ideas and his own personal observations:  whereby each of his ideas rests directly or indirectly on a basis of observation, which alone gives it any real value; and likewise he is able to place every observation that he makes under the right idea corresponding to it.

Maturity of knowledge is the work of experience alone, and consequently of time.  For the knowledge we acquire from our own observation is, as a rule, distinct from that we get through abstract ideas; the former is acquired in the natural way, while the latter comes through good and bad instruction and what other people have told to us.  Consequently, in youth there is generally little harmony and connection between our ideas, which mere expressions have fixed, and our real knowledge, which has been acquired by observation.  Later they both gradually approach and correct each other; but maturity of knowledge does not exist until they have become quite incorporated.  This maturity is quite independent of that other kind of perfection, the standard of which may be high or low, I mean the perfection to which the capacities of an individual may be brought; it is not based on a correspondence between the abstract and intuitive knowledge, but on the degree of intensity of each.

The most necessary thing for the practical man is the attainment of an exact and thorough knowledge of what is really going on in the world; but it is also the most irksome, for a man may continue studying until old age without having learnt all that is to be learnt; while one can master the most important things in the sciences in one’s youth.  In getting such a knowledge of the world, it is as a novice