Full Idea
Nothing monumental has ever emerged from dialogue, nothing explosive, nothing 'great'.
Gist of Idea
No great idea ever emerged from a dialogue
Source
E.M. Cioran (A Short History of Decay [1949], 3)
Book Reference
Cioran,E.M.: 'A Short History of Decay', ed/tr. Howard,Richard [Penguin 2010], p.118
A Reaction
This may be an argument in favour of dialogue! It smacks of the creepier side of Nietzsche's thinking. I suspect individuals have had many great ideas during dialogues, though not as part of them. Greek schools were all dialogue.