ON ACTING: 'True' Emotion
This is a brilliant admonition against bad acting: that is, an actor's emotions should never be worn (played, demonstrated, etc.) as things unto themselves, but must always be felt, performed and hence subsequently be revealed as "impetus" (prelude, causation) to action. Drama, and its attendant emotion, is best defined as character (feeling under duress) revealed in action.
Good acting: In striving for character goals the true enotional dynamic is: we sense, we feel, we act...that is, we do...and in that doing the emotion is honestly and in accordance with life revealed.