In the mail today I received two things that are different, but similar. On the left is my membership card for the Long Now Foundation. On the right is a packet of Ivan tomato seeds from Victory Gardeners.

A line from Stewart Brand about the Long Now /about page: "The point is to explore whatever may be helpful for thinking, understanding, and acting responsibly over long periods of time."
And a line from Victory Gardeners: "We save local family heirlooms from extinction bringing these hardy cultivars to the seed banks, the marketplace and people’s tables."
Long-term responsibility—it's an important consideration. It's a healthy way to behave. It's a worthy mission. Long-term responsibility is what these two items have in common, in their own ways. Long Now promotes it as a way of thinking; Victory Gardeners promote it as a way of planting or eating.
It's not the same thing as the quixotic drive to expand the human lifespan to who knows when—I understand the feeling, to some degree, but I don't share the drive. It's not as healthy. Living forever implies that you might be there to clean up after yourself; long-term responsibility implies being mindful of what you're doing now and how that decision might propagate into the future, well out of your span of control. Heirloom seeds are a complement of that—plant varieties, created and natural, could disappear from existence without some thoughtful people intentionally saving them. You might not be there one day to plant them, but the seeds will be there as an option for someone else to plant. (So, a alternative definition maintenance might be: the conservation of future working options, or maybe optional working futures.)
This is also quixotic. So be it.
Is a future planted with esoteric saved things—seeds or ideas—more valuable than the alternative without them? It's not clear. The future doesn't even exist yet. When it does exist, we won't even be there for most of it, and what we save we won't be thanked for saving.
The future is like the few remaining wilderness areas. It's not valuable, and it's not useful. It's just there. It's an abstract gift that I've found valuable, saved for me by the chance or choice of countless others that I'll never know—a gift that cannot be created, only destroyed or not destroyed. Even the now feels a little larger and richer for having decided to maintain a possible future.
A similar thought, but closer to ourselves::
We are so used to the notion of our own inevitability as life’s dominant species that it is hard to grasp that we are here only because of timely extraterrestrial bangs and other random flukes. The one thing we have in common with all other living things is that for nearly four billion years our ancestors have managed to slip through a series of closing doors every time we needed them to.
—Bill Bryson, A Short History of Nearly Everything (2003)
An alternative definition of maintenance: a keeper-open of doors.