Marx developed a sophisticated theory of labour under capitalism's expanding reproduction but wrote little specifically on immaterial labour. This paper reflects on how to build from Marx's writings a more comprehensive theory of immaterial labour. Integral to this theorisation is bringing in young Marx's writings on alienation and human nature, and praxis read as the 'point of knowledge is to change the world'. Integrating the young and mature work into a single perspective that highlights the actively causal dimension of human creativity and knowledge for the making of history critically adds to and thereby transforms the naturalism and structural determinism of orthodox readings of Marx's Marxism. We relate this theorisation specifically to the project of liberating academic labour from the shackles of its neoliberal containment by making 'knowledge socialism'.