Ivanov, the Stalinist interrogator, is speaking to the Rubashov a loyal son of the Revolution who now needs to go. Rubashov is in prison wandering if and when he will be executed and of what crime he will need to confess. This section here is an interesting discourse on ethics and puts politics into focus.
But the importance of the discussion comes in the last clause of the last sentence:
‘I don’t approve of mixing ideologies,’ Ivanov continued. ‘There are only two conceptions of human ethics, and they are at opposite poles. One of this is Christian and humane, declares the individual to be sacrosanct, and asserts that the rules of arithmetic are not be applied to human units. The other starts from the base principle that a collective aim justifies all means, and not only allows, but demands, that the individual should in every way be subordinated and sacrificed to the community — which may dispose of it as an experimentation rabbit or a sacrificial lamb. The first conception could be anti-vivisection morality, the second, vivisection morality. Humbugs and dilettantes have always tried to to mix the two conceptions; in practice, it is impossible. Whoever is burdened with power and responsibility finds out that on the first occasion that he has to choose; and he is fatally driven to the second alternative. Do you know, since the establishment of Christianity as a state religion, a single example of a state which really followed a Christian policy? You can’t point out one. In times of need — and politics are chronically in a time of need — the rulers were able to evoke “exceptional circumstances”, which demanded exceptional measures of defense. since the existence of nations and classes, they live in a permanent state of mutual self-defense, which forces them to defer to another time the putting into practice of humanism — ‘
Rubashov looked through the window. The melted snow had again frozen and sparkled, an irregular surface of yellow-white crystals. The sentinel on the wall marched up and down with shouldered rifle. The sky was clear but moonless; above the machine-gun turret shimmered the Milky Way.
Darkness at Noon, Arthur Koestler