What is the "great duty" of a Judge in South Africa in Cry, the Beloved Country? Why is it important that he be incorruptible?
The "great duty" of a Judge in South Africa is "to judge and to pronounce sentence, even sentence of death." The Judge does not make the Law; the People make the Law, and if the Law is not fair, it is not the fault of the Judge. The Judge's only duty is to do justice by upholding the Law; if the Law is unjust, he still must uphold it, because that is his job, to do justice according to the Law.
South Africa at the time of the story is a land of great fear. The power is held by the White People, and so it is the White People who make the Law, and the Law is not always fair. In a land of terrible instability and unrest, the Judge is nonetheless looked upon with much reverence, by "men both white and black." The People are proud of their Judges, "because they believe they are incorruptible;" the Judges alone are held in high estimation even when nothing else is certain. Paradoxically, "even the black men have faith in (their Judges), though they do not always have faith in the Law." The incorruptibility that the South Africans, black and white, ascribe to their Judges "is like a lamp set upon a stand, giving light to all that are in the house." This is why it is important that the Judges are indeed incorruptible (Chapter 22).