Examining this again, I'm noticing the universality of the metaphor across cultures and times. Trees themselves are often sacred or significant symbols in various traditions - from the Tree of Life to the Bodhi Tree - but here, the focus isn't on the tree itself but on the relationship between planter and future beneficiary.
What's striking me now is how this idea might relate to hope and optimism. To plant a tree for future generations requires a certain faith that there will be future generations, that civilization will continue, that the space where you plant will remain nurturing for growth. In our current era of environmental crisis and social upheaval, there's something radical about this kind of long-term optimism.
The quote also seems to suggest that understanding life's meaning isn't about achieving some state of enlightenment or revelation - it's about taking actions that acknowledge and honor our place in the larger human story. The phrase "at least started to understand" feels less like a beginner's milestone now and more like an acknowledgment that this fundamental truth needs to be continually rediscovered and reaffirmed through action.