Approaching this again today, I'm drawn to the element of timing - not just in the obvious sense of future versus present, but in the deeper question of when someone is ready to understand this wisdom. The quote suggests there's a particular moment of maturity or development when we become capable of finding meaning in contributing to a future we won't see.
This makes me think about personal growth in a new way. Often we think of growth as accumulating - more knowledge, more experiences, more achievements. But this quote suggests that true growth might sometimes look like reduction - the gradual letting go of the need for personal benefit or recognition. The tree planter has grown not by gaining something, but by becoming comfortable with not gaining.
There's also something powerful here about the relationship between action and identity. The planter isn't described by their profession, their status, or their beliefs - only by this one action and their consciousness about its future impact. Perhaps this suggests that we're most truly ourselves not in what we claim to be or believe, but in the actual choices we make about how our efforts will affect others beyond our time.