I can’t remember who reminded me to look this up, but I rather like,
“What childish innocence it is to present one’s own impatience as a theoretically convincing argument!” (Frederick Engels, “Programme of the Blanquist Communards”, [30] from the German Social-Democratic newspaper Volksstaat, 1874, No. 73
I have sourced this from Lenin’s “Left-Wing” Communism: an Infantile Disorder, hosted at marxists.org
Childish Innocence