help - what was Pablo Neruda's line in his memoir about the poem he wrote for Garcia Lorca?

I vaguely remember him writing about a time when he was giving a public lecture and someone in the audience asked him, “Why did you write the line in your homage to Lorca that said ‘for you they paint the hospital walls blue.’” and Neruda responded by saying something like, “you should never ask a poet ‘why’ he writes anything”...does anyone know the exact quote I’m referring to?? I can’t find it online anywhere and don’t have time to get to a bookstore to look through his memoirs.