course, have to be revised every ten years. Some such arrangement as this would employ the youthful power of the memory to best advantage, and supply excellent working material to the faculty of judgment, when it made its appearance later on.
A man's knowledge may be said to be mature, in other words, to have reached the most complete state of perfection to which he, as an individual, is capable of bringing it, when an exact correspondence is established between the whole of his abstract ideas and the things he has actually perceived for himself. This will mean that each of his abstract ideas rests, directly or indirectly, upon a basis of observation, which alone endows it with any real value; and also that he is able to place every observation he makes under the right abstract idea which belongs to it. Maturity is the work of experience alone; and therefore it requires time. The knowledge we derive from our own observation is usually distinct from that which we acquire through the medium of abstract ideas; the one coming to us in the natural way, the other by what people tell us, and the course of instruction we receive, whether it is good or bad. The result is that in youth there is generally very little agreement or correspondence between our abstract ideas, which are merely phrases fixed in the mind, and that real knowledge which we have obtained by our own observation. It is only later on that a gradual approach takes place between these two kinds of knowledge, accompanied by a mutual correction of error; and knowledge is not mature until this coalition is accomplished. This maturity or perfection of knowledge is something
