From Atomic Movement to Psychic Balance. Order and Disorder in Democritus’ Ethics - Democritus, in the ethical fragments, has frequently recourse to the vocabulary of physical order (equilibrium, balance, mixture), when he describes the main goal of ethics, i.e. the state of cheerfulness or well-being, and some correlated states. Is this compatible with his physics, according to which everything depends on atomic movements? It is argued that, beyond the classical debate about the relation between ethics and physics, the issue of order or organisation, through the idea of physiological balance, lies at the core of Democritus’ ethics. Now, this doctrine of internal equilibrium is at least compatible with his physics. In particular, psychic order and well-being do not abolish physical disorder; they rest on a dynamic organisation, whose stability is merely relative.