Marcus Aurelius on the Present
Were you to live three thousand years, or even thirty thousand, remember that the sole life which a man can lose is that which he is living at the moment; and furthermore, that he can have no other life except the one he loses. This means that the longest life and the shortest amount to the same thing. For the passing minute is every man’s equal possession, but what has once gone by is not ours. Our loss, therefore, is limited to that one fleeting instant, since no one can lose what is already past, nor yet what is still to come–for how can he be deprived of what he does not possess? So two things should be borne in mind. First, that all the cycles of creation since the beginning of time exhibit the same recurring pattern, so that it can make no difference whether you watch the identical spectacle for a hundred years, or for two hundred, or for ever. Secondly, that when the longest- and the shortest-lived of us come to die, their loss is precisely equal. For the sole thing of which any man can be deprived is the present; since this is all he owns, and nobody can lose what is not his.
Marcus Aurelius, from Book II of Meditations