The novel "The Spy Who Came In From the Cold" shows us what it is like to live without humanity. It shows us an upside-down world, in which people are disposable, morals inapplicable and love becomes the biggest danger of all. It tells the story of a spy, Leamas, who found the humanity that was buried inside him, and learned to live and to love. It also shows a conflicting story of a man, Mundt, who lives his entire life without any sense of morality or humanity. Mundt is a man who lives the life of a spy.
The life of a spy is very different to the life of ordinary people. They live in a world where the rules and laws of ordinary life do not apply. "Intelligence work has one moral law - it is justified by results" (page 13). Simplicity and focus are the key elements to being a successful spy. Their world needs to be reduced to black and white. As such, spies cannot afford to display nor have those emotions associated with normal humanity. Any display of compassion is a complication that may get them killed. .
In this sense, the spy is forced to live a life "out in the cold," detached and distanced from others. They need the safety such distance brings to them. Being a spy is a dangerous occupation, and lives are constantly put at risk. Agents need to be focused at all times - they cannot afford to have distractions. If a colleague is killed, there is no time for grief and no room for revenge. They feel that, to call upon an old and overused saying, "the show must go on". Above all there is no room for compassion. With compassion comes the ability to see and value humanity; the ability to see humanity in the enemy and not just a cause for which they are fighting. There is a need for distance between spies and the rest of the world, parallel but very separate. If they do not, they become emotionally vulnerable, and vulnerable people get caught. This is a prominent theme of the book "The Spy Who Came In From The Cold".