H.D.F. Kitto (1897-1982), The Greeks, rev. ed. (1957; rpt. Harmondsworth: Penguin Books, 1967), pp. 36-37 (footnote omitted):

In Greece one can lead an active life on much less food than harsher climates make necessary; but there is also the fact that the Greek — the Greek man — could and did spend most of his leisure hours out of doors. That in itself meant that he had more leisure; he did not need to work in order to buy settees and coal. — After all, the reason why we English have invented 'le confort anglais' is that we cannot be comfortable and warm except indoors. The leisure which the Athenian enjoyed is popularly attributed to the existence of slavery. Slavery had something to do with it, but not so much as the fact that three-quarters of the things which we slave for the Greek simply did without.

So, spending out of doors the leisure which he earned largely by doing without things which we find or think necessary, the Greek, whether in town or village, was able to sharpen his wits and improve his manners through constant intercourse with his fellows. Few people have been so completely sociable. Talk was the breath of life to the Greek — as indeed it still is, though somewhat spoiled by a serious addiction to newspapers. What society but Athens could have produced a figure like Socrates — a man who changed the current of human thought without writing a word, without preaching a doctrine, simply by talking in the streets of a city which he never left but twice — for the battlefield? In what other society is one so little conscious of a chasm between the educated and the uneducated, between those with taste and the vulgar? The real education of the Athenian, and of many another Greek, was given in the places of assembly — in the hours of talk in market-place, colonnade or gymnasium, in the political assembly, in the theatre, at the public recitals of Homer, and at the religious processions and celebrations. For it was perhaps the greatest boon conferred upon Attica by her chmate that her big assemblies could be held in the open air. However democratic the instincts of the Athenian might be, Athenian democracy could not have developed as it did — nor for that matter Athenian Drama — if a roof and walls had been necessary. In our conditions of shelter, privacy and admission-fees, the life of the well-to-do must be potentially richer than the life of the poor, and only six hundred can have direct access to the business of the nation. In Athens all these things could be open to all because they could be open to the air and the sun. To explain Athenian culture simply as the product of the Athenian climate would be foohsh, though not unfashionable; nevertheless it is demonstrable that in a different climate it could not have developed as it did.