V. I. Lenin
Collected Works, Vol. 31
Moscow: Progress Publishers, 1960, pp. 152-3

"Preliminary Draft Theses on the Agrarian Question"

"The industrial workers cannot accomplish their epoch-making
mission. . .if they. . . smugly restrict themselves to attaining an
improvement in their own conditions, which may sometimes be tolerable
in the petty-bourgeois sense. This is exactly what happens to the 'labor
aristocracy' of many advanced countries, who constitute the core of the
so-called socialist parties of the Second International; they are actually
the bitter enemies and betrayers of socialism, petty-bourgeois chauvinists
and agents of the bourgeoisie within the working-class movement."

[MC5 comments: Credit to Dennis McKinsey for bringing this quote and
many others to MIM's attention.]