The Soviet Union needs thinking and critical friends, such as are capable not only of singing hymns in the hours of success, but of not shrinking in the hour of defeat and danger.

[Vladimir] Lenin died in January, 1924; three months later [Joseph] Stalin expounded in writing Lenin's conception of the proletarian revolution.

No one revolution up to now has brought all that was expected of it by the masses. Hence the inevitability of a certain disillusionment, of a lowering of the activity of the vanguard, and consequently, of the growing importance of the rearguard. [Joseph] Stalin's faction has raised itself on the wave of reaction against the October revolution.

The fall of the present bureaucratic dictatorship [in the Soviet Union], if it were not replaced by a new socialist power, would thus mean a return to capitalist relations with a catastrophic decline of industry and culture.

Workers – men and women – of all countries, place yourselves under the banner of the Fourth International. It is the banner of your approaching victory!

National self-sufficiency or "autarchy" is the ideal of [Adolf] Hitler, not of [Karl] Marx and [Vladimir] Lenin.

In a serious struggle there is no worse cruelty than to be magnanimous at an inopportune time.