Of all forms of musical writing, a cappella might be the closest to painting in sound. But don’t take my word for it.
“I’ve never felt so much like a painter than I do when I’m doing vocal arrangements because every note is just, like, you’re adding a little bit of contour. So, like, let me just emphasize that shadow or make that line more defined or add an element of surprise or draw your attention. It’s like you’re commanding all these minutiae of axes that it takes to have an emotional experience. You get to be the controller of that, which is such a privilege, I find, as a harmonist.”
Jacob Collier, in his Logic Session Breakdown of “Bridge Over Troubled Water”
I don’t pretend to be as brilliant an arranger or harmonist as Jacob Collier, nor do I agree with every musical choice he makes. But I completely agree that writing a cappella harmony is just so much like painting. I hear it in his work, but also in Gene Puerling’s pieces, Alice Parker’s pieces, Phil Mattson’s pieces, Anders Edenroth’s pieces, and many many others. Duruflé! Whitacre! And I feel this in the best moments of my writing, too.
The well-chosen harmonic and melodic moments in an a cappella arrangement have the same power as the light in a Rembrandt painting or the contours of a Michelangelo sculpture.