On 21 November The Spectator is hosting a discussion about addiction — disease or choice? — and how we should best treat it. This neatly coincides with ‘Live like a Stoic’ week (25 November–1 December), which culminates in academics and doctors discussing how far problems of everyday life can be solved by the Stoic practice of thinking rationally about them — in modern parlance ‘cognitive behavioural therapy’ — rather than by expensive medical intervention.

Stoicism was invented by Zeno, a Greek from Citium in Cyprus. In about 301 bc, he began teaching in one of Athens’ covered walkways (a stoa, whence ‘stoicism’). His work was to influence two thinkers in particular: Epictetus (c. ad 50–135), a Greek who started life as a slave and ended up leading a famous school of philosophy, consulted (we are told) by the emperor Hadrian; and the ancient world’s most famous doctor, Galen (c. ad 130–210).

Epictetus’s contribution was to insist that we should distinguish between what we can and what we cannot control. We can, he insisted, control what goes on in our head — our beliefs, motives and state of mind; but we cannot control, hard though we may try, our health, property or social standing. Happiness therefore depended not on ‘externals’ like money or society, but on our thought-processes. Think properly, control what we can control, and never come to harm. Galen had a wider vision: a balance that must be maintained between e.g. food and drink, exercise, mental state and so on, and ways of helping patients to achieve this for themselves. Both were practical thinkers, arguing that happiness was in our own hands. Not that it was easy: both insisted that one had to work hard at it by regular, disciplined reflection and action.

Coming soon: an Epicurean week? Not that Epicurus was all fun and frolics. He classified ‘desire’ into three categories: (i) natural and necessary, (ii) natural and unnecessary, and (iii) unnatural and unnecessary, and reckoned only (i) made you happy. Spoil-sport.