You learn to rely on a few basic movements and use your voice to the greatest extent possible to convey your emotions. So there was a technical challenge there and a responsibility to create a character from behind the mask.
“I found that our Soviet espionage efforts had virtually never, or had very seldom, produced any worthwhile political or economic intelligence on the Soviet Union.”
“How can you defy fear? Fear is a human instinct, just like hunger. Whether you like it or not, you become hungry. Similarly with fear. But I have learned to train myself to live with this fear.”