Abstract

The aim of this paper is to show that Epicurus’ notion of quarta natura emerges as a result of his appropriation of an Aristotelian argument against Democritus’ theory of the soul. In order to do so, the paper will be organised as follows. As a starting point, I will consider Cicero’s account of the quintum genus (Tusc. I, 10 22) and offer an evaluation of scholarly debates about his attribution of the theory to Aristotle. By comparing Cicero’s testimony with Lucretius’ one (DRN III, 237-244), I will show that the two accounts retain strong resemblances as to their argumentative structures. In order to account for this closeness, I will offer two interpretative options. (i) On the basis of a later dating of the quintessence theory and its attribution to the Peripatos of the 2nd century BCE, I will attempt an explanation by relying on Lucretius’ own appropriation of the quintessence theory through an argument ‘by subtraction’. Alternatively, (ii) I will examine whether the theory of the fourth nature should be acknowledged to Epicurus already, who borrows the argument by subtraction from Aristotle directly. This option will be verified on the basis of two Aristotelian passages (De Caelo, 296a30-269b2 ; Generation of Animals, 736b29-737a1), where the argument by subtraction introduces, respectively, the ether and the pneuma. Finally, through an analysis of De Anima, 405a 5-7, I will show that option (ii) has interpretative advantages, as it explains Epicurus attempt to counter an Aristotelian critique against Democritus’ theory of the soul.