De Brevitate Vitae, “On The Shortness of Life,” is an essay written by Seneca the Younger in 49 AD. It contains many Stoic principles. I remember translating it in Latin class (well, I wrote a program to do my Latin homework), but many of the passages left an impact on me.
Vīta brevis, ars longa (Life is short, art is long)
So it is—the life we receive is not short, but we make it so, nor do we have any lack of it, but are wasteful of it. Just as great and princely wealth is scattered in a moment when it comes into the hands of a bad owner, while wealth however limited, if it is entrusted to a good guardian, increases by use, so our life is amply long for him who orders it properly.
Vita, si uti scias, longa est. (Life is long if you know how to use it.)
You will find no one willing to share out his money; but to how many does each of us divide up his life! People are frugal in guarding their personal property; but as soon as it comes to squandering time they are most wasteful of the one thing in which it is right to be stingy.
Life is divided into three periods, past, present and future. Of these, the present is short, the future is doubtful, the past is certain.
The part of life we really live is small. For all the rest of existence is not life, but merely time.