What prompted him [Robespierre] to do it [give the speech of 8 Thermidor]? Historians, both defenders and detractors, have argued about the matter ever since. Jean Massin, a staunch supporter, believes it was due to excessive exhaustion, which had become evident since the attempts made on his life in May. Some (and they include Georges Lefebvre) have suggested that he deliberately courted martyrdom when he saw no other clear solution in sight. Gerard Walter inclines towards a similar view: that he felt that his destiny as a champion of “virtue” against “vice” had by now been fulfilled; while Max Gallo, for his part, believes it was a personal choice which put an end to the ‘too long unbearable waiting for martyrdom and the rest.’ (The advantage of this “death-wish” argument is, of course, that it cannot be proved or disproved; so it is a simple case of heads I win, tails you lose!)
Whatever the true explanation, Robespierre had evidently lost his grip. He was heard in silence and the Convention declined to allow him the usual courtesy of sending his speech to be printed.
George Rude, Robespierre: Portrait of a Revolutionary Democrat