But while Greek and Roman riveted oath upon oath and laid ceremony upon ceremony, to accomplish that simple understanding which should be effected by the mere parole of right-thinking men, there is no evidence to show that swearing was carried to the precise point to which it has been brought among ourselves. That at the lightest stir of the emotions they were ready to apostrophise the ruling divinities as well as the shapes of field and flood, of earth and air, must pass as uncontradicted,[18] but never do they appear, as in the modern world, to have forged their poetic oaths into weapons of malevolence and hurt. There would seem to have been no actual counterpart in these languages to the vituperative swearing of modern days. The difference in this respect is somewhat singular, but it may readily be accounted for. With the ancients, oaths were employed in guarding as efficiently as they could the public conscience and the public security. With the moderns they have been for the most part released from this unstable duty, and accordingly, with untrammelled energy and ungovernable vigour, they have entered upon a system of privateering upon their own account. Not only had the ancient mythology to struggle against the constant infraction of the sanctity of the deliberative oath, but the minds of heathen votaries must have been strongly biassed by an acquaintance with instances of light swearing in the gods themselves. To render the practice the less capricious and incontinent, a notion of an individual property or trade-mark in oaths came to be perceptibly encouraged. The specific appropriation of some distinctive oath raised the presumption that it implied an unequivocal pledge of sincerity. In this way Zeno, the founder of the Stoics, swore continually "by the caper." Pythagoras, we are told, was accustomed to swear by the number four, [Greek: ma ten tetrakton]. This numeral came to be regarded in consequence as symbolical of the divinity, and the Pythagorean school gravely inculcated it as a point of morals to abstain from intruding upon so illustrious an example.