In youth it is the outward aspect of things that most engages us; while in age, thought or reflection is the predominating quality of the mind. Hence, youth is the time for poetry, and age is more inclined to philosophy. In practical affairs it is the same: a man shapes his resolutions in youth more by the impression that the outward world makes upon him; whereas, when he is old, it is thought that determines his actions. This is partly to be explained by the fact that it is only when a man is old that the results of outward observation are present in sufficient 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.