Have you ever had something happen to you that there was simply no explanation for? That you can't chalk up to a coincidence, or an accident, or even fate?
The green thumb is equable in the face of nature's uncertainties; he moves among her mysteries without feeling the need for control or explanations or once-and-for-all solutions. To garden well is to be happy amid the babble of the objective world, untroubled by its refusal to be reduced by our ideas of it, its indomitable rankness.