Of the coincidence of past and future
This post is not exactly about the "coincidence of past and future".
Most people say "We are building our future". I disagree. We are not building our future. We are building our descendant's past.
Why do I say so? For two reasons. One is merely rational. It is in fact illogical to think of building your own future when we are fully aware of the fact that we are doomed, we will die in a relatively brief span of time. Very few things can be "built" in a lifetime, at least very few things that really matter. But many can be started. Of course, some great men like Alexander the Great could forge an Empire in less than a lifetime, but there aren't many men like Alexander.
Building one's future is highly unlikely to succeed. Besides, we have no idea if we'll still be alive tomorrow, so what future are we talking about?
The second reason is philosophical.
We don't exist out of the blue. We, our civilization, our ethics, our beliefs, everything we know of, is a consequence of all the things that happened before, the combination of all the deeds performed by those that came before us. Knowingly or unknowingly, Alexander the Great, Julius Ceasar, Charlemagne, Leonardo, Michaelangelo, Voltaire, Jefferson, Napoleon and Churchill weren't as much building their future as they were posing the roots for our past. We have inherited the world each one of them created, step by step, and we share the same responsibility toward those that will follow us. We should not let our civilization degrade in a craving for instant satisfaction and immediate pleasure, for our descendants will build upon the grounds we set for them. We must promote civilization toward novel routes, so that our descendants will have a richer past to look at when they will continue our work.
The future doesn't really exist yet; the past instead is very real and constitutes the basis from which we moved our first steps in the world. I think the world would move on a better route if we all thought we are not building our future, as if we were the last generation to ever live, but rather building the past of our descendants, who will build the past of their descendants, and so on, in a continuous struggle to improve what was given us by our ancestors.