The quote is about gardens and the metaphorical "garden" that is the space for growth and creativity in our own lives:
The good life is lived best by those with gardens — a truth that was already a gnarled old vine in ancient Rome, but a sturdy one that still bears fruit. I don’t mean one must garden qua garden… I mean rather the moral equivalent of a garden — the virtual garden. I posit that life is better when you possess a sustaining practice that holds your desire, demands your attention, and requires effort; a plot of ground that gratifies the wish to labor and create — and, by so doing, to rule over an imagined world of your own.
That last line is what inspired today's growth cat:
I rule an imagined world of my own.