During the lifetime of great revolutionaries, the oppressing classes constantly hounded them, received their theories with the most savage malice, the most furious hatred and the most unscrupulous campaigns of lies and slander. After their death, attempts are made to convert them into harmless icons, to canonize them, so to say, and to hallow their names to a certain extent for the โconsolationโ of the oppressed classes and with the object of duping the latter, while at the same time robbing the revolutionary theory of its substance, blunting its revolutionary edge and vulgarizing it.
Vladimir LeninThe whole struggle of our Party (and of the working class movement in Europe generally) must be directed against opportunism. The latter is not a current of opinion, not a tendency; it (opportunism) has now become the organised tool of the bourgeoisie within the working class movement.
Vladimir Lenin