In the short span of his lifetime, an actor must learn all there is to know, experience all there is to experience, or approach that state as closely as possible. He must be superhuman in his efforts to store away in the core of his subconscious everything that he might be called upon to use in the expression of his art.
As quoted in: The unabridged James Dean: his life and legacy from A to Z (McGraw-Hill/Contemporary, 1991), p. 409