Of all the reasons why punishment that was not in the least ashamed of being ‘atrocious’ was replaced by punishment that was to claim the honour of being ‘humane’ there is one that must be analysed at once, for it is internal to the public execution itself: at once an element of its functioning and the principle of its perpetual disorder.
In the ceremonies of the public execution, the main character was the people, whose real and immediate presence was required for the performance. An execution that was known to be taking place, but which did so in secret, would scarcely have had any meaning. The aim was to make an example, not only by making people aware that the slightest offence was likely to be punished, but by arousing feelings of terror by the spectacle of power letting its anger fall upon the guilty person: ‘In criminal matters, the most difficult point is the imposition of the penalty: it is the aim and the end of the procedure, and its only fruit, by example and terror, when it is well applied to the guilty person’.
— Michel Foucault (1926-1984)