the essential nature

The actor takes the mask, studies it, and as he puts it on, his face slightly modifies itself until it goes towards the shape of the mask, and he puts it on his face and in a way he has dropped one of his own masks; so the intervening flesh masks disappear and the actor is in close contact, epidermal contact, with a face that is not his face, but the face of a very strong, essential type of man. And his actor's capacity to be a comedian (without which he couldn't be an actor) makes him realize his potentiality to be that person. So at that moment he is in that role. And that becomes his role; and the moment it is assumed, it comes to life, it is no longer hard and fast but something that adapts itself to any circumstance; so the actor, having put that mask on, is sufficiently in the character that if someone unexpectedly offers him a cup of tea, whatever response he makes is totally that of that type, not in the schematic sense but in the essential sense. For instance, if he's wearing a proud mask, in the schematic sense he would be forced to say proudly, "Take away your tea!" But in a living sense, the proudest of men can see a cup of tea and say, "Oh, thank you," and take it without betraying his essential nature.

-- Peter Brook