Another reason why life looks so long when we are young, is that we are apt to measure its length by the few years we have already lived. In those early years things are new to us, and so they appear important; we dwell upon them after they have happened and often call them to mind; and thus in youth life seems replete with incident, and therefore of long duration. Sometimes we credit ourselves with a longing to be in some distant spot, whereas, in truth, we are only longing to have the time back again which we spent there--days when we were younger and fresher than we are now. In those moments Time mocks us by wearing the mask of space; and if we travel to the spot, we can see how much we have been deceived. There are two ways of reaching a great age, both of which presuppose a sound constitution as a _conditio sine quâ non_. They may be illustrated by two lamps, one of which burns a long time with very little oil, because it has a very thin wick; and the other just as long, though it has a very thick one, because there is plenty of oil to feed it. Here, the oil is the vital energy, and the difference in the wick is the manifold way in which the vital energy is used. Up to our thirty-sixth year, we may be compared, in respect of the way in which we use our vital energy, to people who live on the interest of their money: what they spend to-day, they have again to-morrow. But from the age of thirty-six onwards, our position is like that of the investor who begins to entrench upon his capital. At first he hardly notices any difference at all, as the greater part of his expenses is covered by the interest of his securities; and if the deficit is but slight, he pays no attention to it. But the deficit goes on increasing, until he awakes to the fact that it is becoming more serious every day: his position becomes less and less secure, and he feels himself growing poorer and poorer, while he has no expectation of this drain upon his resources coming to an end. His fall from wealth to poverty becomes faster every moment--like the fall of a solid body in space, until at last he has absolutely nothing left. A man is truly in a woeful plight if both the terms of this comparison--his vital energy and his wealth--really begin to melt away at one and the same time. It is the dread of this calamity that makes love of possession increase with age. On the other hand, at the beginning of life, in the years before we attain majority, and for some little time afterwards--the state of our vital energy puts us on a level with those who each year lay by a part of their interest and add it to their capital: in other words, not only does their interest come in regularly, but the capital is constantly receiving additions. This happy condition of affairs is sometimes brought about--with health as with money--under the watchful care of some honest guardian. O happy youth, and sad old age!