We all die and hopefully most of us live life as well. In the end we are all tears in the rain but that doesn't make our experience less important or less valuable.
To be lost and forgotten is perhaps our greatest blessing. We may lose all the joys of life, but we also lose the pains and regrets of life too, and we have the happy knowledge that we shall no longer a burden to the world or its people, not even in memory.
I have been a gardener all my life, and created, or helped create, many lovely gardens. ( If I may be so immodest for the sake of argument. ) Yet gardens are the most ephemeral of all the arts, neglect them for a year or two, and they are gone, nobody will hang my gardens on a gallery wall for future generations to waste their time and thought on, wondering wrongly what an old man intended. When they are gone, new young people, hansom young men and pretty girls in gardening boots too big for their dainty feet, will take those spaces and make beautiful new gardens of their own, for their children to play in. And that is the true comfort for mortality, the renewing quality of life.
While if the human race kills the planet, and with it, all the gardens, both man made and natural, in its greed and shallowness, then at least I shall not see it, and can say. "Screw you lot. Let the world go to whatever small creature crawls out of the ruins, surviving hard times, and evolving, earns you a few hours sitting in the garden at least."
I recall a quote from someone or other that simply said 'A culture grows great when old men plant trees who shade they will live long enough to enjoy.' Planting a garden is the greatest act of rebellion against our current system of exploitation and greed.