A well directed sitting will have something of the quality of a good plan - a constant building and development of tension and excitement. The interest of the model and artist should both be carried along in the current of common enthusiasm. To make the sitting move in this way, the artist must work, must give of himself. An artist who finishes a sitting with his respiration, pulse and the part of his hair unaltered, has probably obtained very poor results.

The Model - A Book on the Problems of Posing, Cameracraft Publishing 1937 p.196