Without pushing the analogies too far, there are some lessons here that can be applied to the Iranian case.

First, these revolutionary excesses—the show trials in Moscow and the madness of the Red Guards during the Cultural Revolution in China—both occurred in the context of the consolidation of power by a single leader who feared the rivalry of those who had been with him on the ramparts and who had shared power as the revolution stabilized…

Second, events of this nature grow out of ideological paranoia. As people emerge from the exaltation of their revolutionary triumph and begin to confront the realities of governing a country, tensions inevitably arise between the purity of the ideals of the revolution and the mundane choices of day-to-day rule. It seems to be inevitable that a set of radical leaders claim primacy as the only authoritative interpreters of the revolution and conclude that only they can be trusted to insure its survival…

Third, terror becomes a habit. Security forces are mobilized to enforce the paranoid concerns of their superiors. Instead of being horrified, they come to see it as a natural part of their job. It becomes routine and utterly banal, as in Hannah Arendt’s formulation of evil.

Finally, the internal dynamics of fear, greed, paranoia and rivalry for power feed on themselves and carry the process to excess that is difficult to comprehend, even in retrospect. Iran is still at the early stages of this process.