The discipline of the sitting, from the studio to the street.
David Bailey. He met Jean Shrimpton in 1960, insisted on casting her against his editors' wishes, and later said, "I think we created each other": the model's half of the portrait, the micro-decisions of posture and expression, is invisible labor the camera keeps.
The great fashion portraits were rarely made in a single session. They were made across years of sittings, between a photographer and a model who taught each other how to see. On collaboration as authorship.