The only solemn oath, by which the gods irrevocably obliged themselves, is a well-known thing, and makes a part of many ancient fables. To this oath they did not invoke any celestial divinity, or divine attribute, but only called to witness the river Styx; which, with many meanders, surrounds the infernal court of Dis. For this form alone, and none. but this, was held inviolable and obligatory: and the punishment of falsifying it, was that dreaded one of being excluded, for a certain number of years, from the table of the gods.
This fable seems invented to show the nature of the compacts and confederacies of princes: which, though ever so solemnly and religiously sworn to, prove but little the more binding for it: so that oaths in this case seem used, rather for decorum, reputation, and ceremony, than for fidelity, security, and effectuating. And though these oaths were strengthened with the bonds of affinity, which are the links and ties of nature, and again, by mutual services and good offices, yet we see all this will generally give way to ambition, convenience, and the thirst of power: the rather, because it is easy for princes under various specious pretences, to defend, disguise, and conceal their ambitious desires and insincerity; having no judge to call them to account. There is, however, one true and proper confirmation of their faith, though no celestial divinity; but that great divinity of princes, Necessity; or, the danger of the state; and the securing of advantage.
This necessity is elegantly represented by Styx, the fatal river, that can never be crossed back. And this deity it was, which Iphicrates the Athenian invoked in making a league: and because he roundly and openly avows what most others studiously conceal, it may be proper to give his own words. Observing that the Lacedæmonians were inventing and proposing a variety of securities, sanctions, and bonds of alliance, he interrupted them thus:
'There may indeed, my friends, be one bond and means of security between us: and that is, for you to demonstrate you have delivered into our hands, such things as that if you had the greatest desire to hurt us you could not be able'.
Therefore, if the power of offending be taken away, or if by a breach of compact there be danger of destruction or diminution to the state or tribute, then it is that covenants will be ratified, and confirmed, as it were by the Stygian oath, whilst there remains an impending danger of being prohibited and excluded the banquet of the gods; by which expression the ancients denoted the rights and prerogatives, the affluence and the felicities, of empire and dominion.