Full Idea
Destroy the seriousness of others with laughter, and their laughter with seriousness.
Gist of Idea
Destroy seriousness with laughter, and laughter with seriousness
Source
Gorgias (fragments/reports [c.443 BCE]), quoted by Aristotle - The Art of Rhetoric 1419b
Book Reference
Aristotle: 'The Art of Rhetoric', ed/tr. Lawson-Tancred,H.C. [Penguin 1991], p.260
A Reaction
This sounds like brilliant tactical advice, which should be on the wall of every barrister's chambers. This is a case of rhetoric having something to teach us which is nothing at all to do with truth. It is more like learning karate.