It occurred to me that a writer has to experience the emotions of the characters fully, but inwardly, and then transfer that to the page.
Whereas the actor obviously experiences the emotions outwardly. They're opposite sides of the same coin.
The director is some amorphous in-between, perhaps in the analogy they are the coin themselves. They have to translate the emotion from inward to outward and also create a conducive world wherein the emotion feels conducive and real.