Ernest Newman, on accuracy in Berlioz's "Memoires"

It is more than doubtful whether any such incident took place, however. There is no mention of it in any of the newspaper accounts of the performance, nor does Berlioz refer to it in his letter of the 17th to Humbert Ferrand: he merely says that “The Requiem was done well.” He is equally silent as to the snuff-box crime in his letter of the same day to his mother.

Did Berlioz, I often wonder, in the later years when he was eaten away with disappointments of every kind, dream things under the influence of the opium he had to take to dull his pains, and then, in waking hours, transfer his dream to the past as reality?

-in relation to the "Snuff Box Incident" during the first performance of Berlioz's Requiem. According to Berlioz, the conductor François-Antoine Habeneck set down his baton during the attaca between the Dies irae and the Tuba mirum to take a pinch of snuff. Berlioz claims to have jumped from his front row seat, pushed him off the podium, and took over conducting, saving his performance from certain ruin, even speculating this had been a conspiracy instigated by the Director of Fine Arts and Cherubini, both whom he quarreled with regularly. From a footnote in Memoirs of Hector Berlioz, 1932 printing annotated by Newman. p 210n1.