I shall call Ideological State Apparatuses (ISAs) a certain number of realities which present themselves to the immediate observer in the form of dis… - Louis Althusser

To become 'ideologists of the working class' (Lenin), 'organic intellectuals' of the proletariat (Gramsci), intellectuals have to carry out a radical revolution in their ideas: a long, painful and difficult re-education. An endless external and internal struggle.

Class instinct is subjective and spontaneous. ... To arrive at proletarian class positions, the class instinct of proletarians only needs to be educated; the class instinct of the petty bourgeoisie, and hence of intellectuals, has, on the contrary, to be revolutionized.

Like every 'intellectual', a philosophy teacher is a petty bourgeois. When he opens his mouth, it is petty-bourgeois ideology that speaks: its resources and ruses are infinite.