It was probably some ingenious fancy, of comparing the thirty tyrants of Rome with the thirty tyrants of… — Edward Gibbon

It was probably some ingenious fancy, of comparing the thirty tyrants of Rome with the thirty tyrants of Athens, that induced the writers of the Augustan History to select that celebrated number, which has been gradually received into a popular appellation. But in every light the parallel is idle and defective. What resemblance can we discover between a council of thirty persons, the united oppressors of a single city, and an uncertain list of independent rivals, who rose and fell in irregular succession through the extent of a vast empire? Nor can the number of thirty be completed, unless we include in the account the women and children who were honoured with the Imperial title.

Source: Wikiquote · CC BY-SA 4.0