The iceberg image is a bit more in the right direction. Some early research on creativity did seem to come back with the result "if you're happy you'll be more creative", but https://www.zorana-ivcevic-pringle.com/ dug a bit deeper and suggested that its about leveraging all sorts of emotions.

So broadly (maybe I'm stretching) it's about dragging the unconscious into consciousness, whatever it may be saying.