Inscribed in the forecourt of the temple of Apollo in Delphi were the famous words gnôthi sauton (‘know yourself’) and mêden agan (‘nothing in excess’). They should be re-inscribed in the chamber of the House of Commons, and especially on every piece of paper that passes across the desk of the hapless Jeremy Corbyn.

The ancients were all too aware that life was characterised by man’s weakness, ignorance and vulnerability to sudden, unpredictable reversals of fortune. Although one reaction was to eat, drink and be merry, pessimism was the Greeks’ default position to the world about them. Struck by the way in which their myths returned again and again to the theme of the powerful brought low at the peak of their fortune, they were predisposed to find this pattern duplicated in their history: the fabulously wealthy Lydian king Croesus, convinced he was the happiest man in the world, crushed by failing to understand the oracles; Xerxes, proud king of mighty Persia, humbled by the Greeks at Salamis.

To judge from Greek tragedy, one refrain consistently underpins the pattern: a failure of self-awareness. The cry ‘Too late I understand’ echoes through the tragedians’ works. The Oedipus story is paradigmatic of such human frailty: the man of high intelligence who, thinking that he was son of the king of Corinth, killed his father, the king of Thebes, and married his mother. For Greeks, in other words, gnôthi sauton meant at heart ‘Know your limitations — what you can and more importantly cannot do’. Mêden agan was the other side of the coin: go too far and you are asking for trouble.

And so to Jeremy Corbyn, the perpetual protestor who, mesmerised by unexpected power, does not seem to understand that he has never had, nor ever will have, the capacities required of a leader, but is simply the pathetic stooge of a small group of left-wing delusionists who know that if he goes, their fantasy world vanishes in a puff of smoke. Whether he ever will understand remains to be seen.