The Prehistory of Godwin’s Law

From Harpo Marx’s autobiography, regarding his New York City pals:

They had changed along with the times. Seven or eight years ago we would have wound up an all-night party in Aleck’s apartment arguing about croquet or the stock market, or making up wild puns and nasty menus. Now we wound up talking (they did, I mean—I still listened) about the NRA, the CCC, FDR’s last Fireside Chat, and Fiorello La Guardia, the new mayor of New York. Sooner or later Adolf Hitler entered every conversation, which killed it, and everybody went home wrapped up in his own depressing thoughts.