The examination transformed the economy of visibility into the exercise of power. Traditionally, power was what was seen, what was shown and what was manifested and, paradoxically, found the principle of its force in the movement by which it deployed that force. Those on whom it was exercised could remain in the shade; they received light only from that portion of power that was conceded to them, or from the reflection of it that for a moment they carried. Disciplinary power, on the other hand, is exercised through its invisibility; at the same time it imposes on those whom it subjects a principle of compulsory visibility. In discipline, it is the subjects who have to be seen. Their visibility assures the hold of the power that is exercised over them. It is the fact of being constantly seen, of being able always to be seen, that maintains the disciplined individual in his subjection. And the examination is the technique by which power, instead of emitting the signs of its potency, instead of imposing its mark on its subjects, holds them in a mechanism of objectification. In this space of domination, disciplinary power manifests its potency, essentially, by arranging objects. The examination is, as it were, the ceremony of this objectification.

— surveil-and-punishch. III.2

Compare: ancient Chinese imperial examinations. The Chinese basically invented the exam (~ with the early scale the Chinese state was able to get to + the bureaucracy required to govern it). Role of discipline (administration) in mass societies, vs role of punishment (power play) in vernacular societies.