The mind, a bodily organ

The Epicureans assert that the mind is a part of the body, no less than a hand or an eye (DRN III 94ff.). Just as the heart is the bodily organ responsible for pumping blood through the body, so too the mind is the bodily organ responsible for sensation, thought and memory (Ep. Hdt. 63).

The Epicurean theory obviously has affinities to current identity theories of mind, but the physiology is different. Whereas current identity theorists identify the mind with the brain, Epicurus goes along with the view, common (although not universally held) at his time, of locating it in the chest. Lucretius argues for this location by noting that the centre of the chest is where we feel fear, dread and joy; think of the gaping feeling there when you are startled, for instance (DRN III 136–44). Likewise, just as mental processes are identified with neural processes by current identity theorists, the Epicureans identify mental processes with atomic processes, for example the raving that accompanies epilepsy occurs because the atoms that constitute the mind are being tossed about like water frothing during a storm (DRN III 487–95). The mind is made up of four different sorts of particles: heat, air, wind and a nameless fourth element (Aëtius 4.3.11, LS 14C, DRN III 231–57).