William Boyd said this quote

“ I walked out this evening to the bottom of the garden and smoked a cigarette. Last week I planted an acer in the furthest bed from the house, in honour of our new baby. The sapling is as tall as me and, by all accounts, it can grow forty feet tall. So, in thirty year's time, if we're still here I can come back and see this tree in its maturity. But the thought depresses me: in thirty years' time I'll be in my mid-sixties and I realize that these forward projections that you make, so unreflectingly, in your life are beginning to run out. Suppose I'd said in forty years' time? That would be pushing it, Fifty? I'll probably be gone by then. Sixty? Dead and buried, for sure. Thank Christ I didn't plant an oak. Is that a good definition of of marking the ageing watershed? That moment when you realize-quite rationally, quite unemotionally-that the world in the not-so-distant future will not contain you: that the trees you planted will continue growing but you will not be there to see them. ”