From Seneca On the Shortness of Life:
That advocate is lionized throughout the whole forum, and fills all the place with a great crowd that stretches farther than he can be heard, yet he says: "When will vacation time come?" Everyone hurries his life on and suffers from a yearning for the future and a weariness of the present. But he who bestows all of his time on his own needs, who plans out every day as if it were his last, neither longs for nor fears the morrow. For what new pleasure is there that any hour can now bring? They are all known, all have been enjoyed to the full. Mistress Fortune may deal out the rest as she likes; his life has already found safety. Something may be added to it, but nothing taken from it, and he will take any addition as the man who is satisfied and filled takes the food which he does not desire and yet can hold. And so there is no reason for you to think that any man has lived long because he has grey hairs or wrinkles; he has not lived long—he has existed long. For what if you should think that that man had had a long voyage who had been caught by a fierce storm as soon as he left harbour, and, swept hither and thither by a succession of winds that raged from different quarters, had been driven in a circle around the same course? Not much voyaging did he have, but much tossing about.
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Life is divided into three periods—that which has been, that which is, that which will be. Of these the present time is short, the future is doubtful, the past is certain. For the last is the one over which Fortune has lost control, is the one which cannot be brought back under any man's power. But men who are engrossed lose this; for they have no time to look back upon the past, and even if they should have, it is not pleasant to recall something they must view with regret. They are, therefore, unwilling to direct their thoughts backward to ill-spent hours, and those whose vices become obvious if they review the past, even the vices which were disguised under some allurement of momentary pleasure, do not have the courage to revert to those hours. No one willingly turns his thought back to the past, unless all his acts have been submitted to the censorship of his conscience, which is never deceived; he who has ambitiously coveted, proudly scorned, recklessly conquered, treacherously betrayed, greedily seized, or lavishly squandered, must needs fear his own memory. And yet this is the part of our time that is sacred and set apart, put beyond the reach of all human mishaps, and removed from the dominion of Fortune, the part which is disquieted by no want, by no fear, by no attacks of disease; this can neither be troubled nor be snatched away—it is an everlasting and unanxious possession. The present offers only one day at a time, and each by minutes; but all the days of past time will appear when you bid them, they will suffer you to behold them and keep them at your will—a thing which those who are engrossed have no time to do. The mind that is untroubled and tranquil has the power to roam into all the parts of its life; but the minds of the engrossed, just as if weighted by a yoke, cannot turn and look behind. And so their life vanishes into an abyss; and as it does no good, no matter how much water you pour into a vessel, if there is no bottom21 to receive and hold it, so with time—it makes no difference how much is given; if there is nothing for it to settle upon, it passes out through the chinks and holes of the mind. Present time is very brief, so brief, indeed, that to some there seems to be none; for it is always in motion, it ever flows and hurries on; it ceases to be before it has come, and can no more brook delay than the firmament or the stars, whose ever unresting movement never lets them abide in the same track. The engrossed, therefore, are concerned with present time alone, and it is so brief that it cannot be grasped, and even this is filched away from them, distracted as they are among many things.
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And so when you see a man often wearing the robe of office, when you see one whose name is famous in the Forum, do not envy him; those things are bought at the price of life. They will waste all their years, in order that they may have one year reckoned by their name. Life has left some in the midst of their first struggles, before they could climb up to the height of their ambition; some, when they have crawled up through a thousand indignities to the crowning dignity, have been possessed by the unhappy thought that they have but toiled for an inscription on a tomb; some who have come to extreme old age, while they adjusted it to new hopes as if it were youth, have had it fail from sheer weakness in the midst of their great and shameless endeavours. Shameful is he whose breath leaves him in the midst of a trial when, advanced in years and still courting the applause of an ignorant circle, he is pleading for some litigant who is the veriest stranger; disgraceful is he who, exhausted more quickly by his mode of living than by his labour, collapses in the very midst of his duties; disgraceful is he who dies in the act of receiving payments on account, and draws a smile from his long delayed heir.