Vincent van Gogh is on my mind again these days. Those Don McLean lyrics—“Starry, starry night, Paint your palette blue and grey, Look out on a summer's day, With eyes that know the darkness in my soul”—are playing over and over again in my head. (1) I have always loved van Gogh’s artwork—who isn’t moved by the sadness of Old Man in Sorrow, the humility of The Potato Eaters, the swirling shades of blue in Starry Night, or the striking beauty of his Irises—and, as a psychologist, I’ve long bee...