Seneca

Meanwhile they take no account of time, of which they will never have a fresh and larger supply: they substitute new occupations for old ones, one hope leads to another, one ambition to another: they do not seek for an end to their wretchedness, but they change its subject.

Everything for which we are dependent on chance is uncertain: the higher it rises, the more opportunities it has of falling. Moreover, no one takes any pleasure in what is about to fall into ruin: very wretched, therefore, as well as very short must be the lives of those who work very hard to gain what they must work even harder to keep: they obtain what they wish with infinite labour, and they hold what they have obtained with fear and trembling.

All the greatest blessings are enjoyed with fear, and no thing is so untrustworthy as extreme prosperity: we require fresh strokes of good fortune to enable us to keep that which we are enjoying, and even those of our prayers which are answered require fresh prayers.

That most arrogant Persian king, when his army stretched over vast plains and could not be counted but only measured, burst into tears at the thought that in less than a hundred years none of all those warriors would be alive: yet their death was brought upon them by the very man who wept over it, who was about to destroy some of them by sea, some on land, some in battle, and some in flight, and who would in a very short space of time put an end to those about whose hundredth year he showed such solicitude.

Meanwhile they take no account of time, of which they will never have a fresh and larger supply: they substitute new occupations for old ones, one hope leads to another, one ambition to another: they do not seek for an end to their wretchedness, but they change its subject.