For the Stoics the world is an integrated and structured whole whose parts are active and powerful and which tend towards their realisation unless impeded by some obstacle. Like the giants of Plato’s Sophist (247d-248c), the Stoics think that everything which exists or obtains is corporeal and it is defined, in part, by its power: its being capable of acting or being acted upon (S.E. M. 8.263). They divide the world into two principles: god or pneuma (which acts) and matter (which is acted upon). These are the building blocks out of which other things (even the elements) are, in some sense, composed. Both are corporeal and immanent with bodies and in physical processes God or pneuma acts upon matter and infuses it with powerful qualities. The precise details of this account is open to debate and will be investigated by the project.

For Epicurus, the universe is composed of body and void. The void is empty space – a vacuum. Those bodies observable by humans in the world are themselves ultimately composed of ‘atoms’ – indivisible (‘atomic’) and unchanging bodies.  These are identified as that which will either act upon something or itself be acted upon by other things (Lucr. 1.440-2) and are causally powerful ‘seeds’. All bodies are extended and have weight and resistance (e.g. S.E. M. 10.240) and it is in virtue of these properties that they are inclined towards motion. In addition, compound bodies also have other properties, notably sensible properties (e.g. colour, taste). The precise nature (dispositional or otherwise) of these properties and precisely how and whether they are reducible to or emergent from more fundamental properties is open to debate and will be investigated by the project.

Further Reading:
Cambiano, G. 1997. “L'atomismo antico”, Quaderni di Storia 23: 5–17.
Long, A.A. 1975. “Heraclitus and Stoicism”, Philosophia 5: 133- 156.
Morel, P. 2000. Atome et nécessité: Démocrite, Épicure, Lucrèce. Paris.
Rist, J. ed. 1978. The Stoics. Berkeley.
Sedley, D. 1988. “Epicurean anti-reductionism” in J. Barnes and M. Mignucci edd. Matter and Metaphysics, 295-327. Naples.
Solmsen, F. 1977. “Epicurus on void, matter and genesis”, Phronesis 22: 263-281.
Sorabji, R. 1988. Matter, Space and Motion: Theories in Antiquity and Their Sequel. London.