One assumes that it will eventually dawn on those so deeply committed to slaughtering each other in Syria that, whatever interest they represent, diplomacy is the only way they will ever reach some sort of settlement that will allow some sort of normality to return. Ancients knew all about treaties, and ancient Greeks had a particularly interesting condition which they always imposed.

The Latin for ‘peace’ is pax, which derives from a verb meaning ‘agree to a price, reach a settlement, make an arrangement’ and even ‘engage oneself to marry’. The Latin for ‘treaty’ is foedus (cf. our ‘federation’), associated with a word meaning ‘trust, good faith’. In the end it is all about one’s word.

To ensure it was kept, ancients regularly sealed their treaties with an oath in the name of the gods. This involved the gods in overseeing a fallible human agreement. The theory was that anyone who broke it would therefore be subject to divine as well as human retribution. On the human level, hostages of a suitably high status could be exchanged, and the terms of the treaty would be made public, for all to see. Given that the gods guaranteed the treaty’s force, such terms were often erected in sanctuaries.

But actions speak louder than words, and at the very heart of Greek treaties was the word summakhia. Normally translated ‘alliance’, it literally means ‘fighting together’ i.e. an agreement to wage war together against anyone who attacked any of the treaty’s signatories. Thus when Sparta and Athens, sworn and bitter enemies, agreed terms in 421 bc, the treaty laid down that ‘in case of enemy invasion of or hostile action against Sparta, Athens will come to their aid…’ etc. etc. and vice-versa. Another ancient treaty talks of ‘having the same friends and enemies’.

But how could one possibly persuade Syria’s myriad factions to agree to that? Only by providing them with a mutual enemy hated and feared enough by all sides. Time therefore for the Americans and Brits to intervene.