This chapter turns to Karl Marx’s treatment of Epicureanism and Lucretius in his doctoral dissertation, and argues that the questions raised by Marx may be brought to bear on our own understanding of Epicurean philosophy, particularly in respect of a tension between determinism and individual self-consciousness in a universe governed by material causation. Following the contours of Marx’s dissertation, the chapter focusses on three key topics: the difference between Democritus’ and Epicurus’ methods of philosophy; the swerve of the atom; and the so-called ‘meteors’, or heavenly bodies. Marx sought to develop Hegel’s understanding of Epicurus, in particular by elevating the principle of autonomous action to a first form of self-consciousness – a consideration largely mediated by Lucretius’ theorization of the atomic swerve and his poem’s overarching framework of liberating humans from the oppression of the gods.