numbers to allow of their being classified according to the ideas they represent,—­a process which in its turn causes those ideas to be more fully understood in all their bearings, and the exact value and amount of trust to be placed in them, fixed and determined; while at the same time he has grown accustomed to the impressions produced by the various phenomena of life, and their effects on him are no longer what they were.  Contrarily, in youth, the impressions that things make, that is to say, the outward aspects of life, are so overpoweringly strong, especially in the case of people of lively and imaginative disposition, that they view the world like a picture; and their chief concern is the figure they cut in it, the appearance they present; nay, they are unaware of the extent to which this is the case.  It is a quality of mind that shows itself—­if in no other way—­in that personal vanity, and that love of fine clothes, which distinguish young people.

There can be no doubt that the intellectual powers are most capable of enduring great and sustained efforts in youth, up to the age of thirty-five at latest; from which period their strength begins to decline, though very gradually.  Still, the later years of life, and even old age itself, are not without their intellectual compensation.  It is only then that a man can be said to be really rich in experience or in learning; he has then had time and opportunity enough to enable him to see and think over life from all its sides; he has been able to compare one thing with another, and to discover points of contact and connecting links, so that only then are the true relations of things rightly understood.  Further, in old age there comes an increased depth in the knowledge that was acquired in youth; a man has now many more illustrations of any ideas he may have attained; things which he thought he knew when he was young, he now knows in reality.  And besides, his range of knowledge is wider; and in whatever direction it extends, it is thorough, and therefore formed into a consistent and connected whole; whereas in youth knowledge is always defective and fragmentary.

A complete and adequate notion of life can never be attained by any one who does not reach old age; for it is only the old man who sees life whole and knows its natural course; it is only he who is acquainted—­and this is most important—­not only with its entrance, like the rest of mankind, but with its exit too; so that he alone has a full sense of its utter vanity; whilst the others never cease to labor under the false notion that everything will come right in the end.

On the other hand, there is more conceptive power in youth, and at that time of life a man can make more out of the little that he knows.  In age, judgment, penetration and thoroughness predominate.  Youth is the time for amassing the material for a knowledge of the world that shall be distinctive and peculiar,—­for an original view of life, in other words, the legacy that a man of genius leaves to his fellow-men; it is, however, only in later years that he becomes master of his material.  Accordingly it will be found that, as a rule, a great writer gives his best work to the world when he is about fifty years of age.  But though the tree of knowledge must reach its full height before it can bear fruit, the roots of it lie in youth.