6 Where shall we swear to obey your laws and commands? By what religious sanction shall the false mind be terrified, so as not to lie in bearing witness? All things are indeed filled with God, and no place is safe for the perjured, but to be urged in the very presence of religious forms has great power in producing a fear of sinning. That altar preserves the concord of all, that altar appeals to the good faith of each, and nothing gives more authority to our decrees than that the whole of our order issues every decree as it were under the sanction of an oath. So that a place will be opened to perjury, and this will be determined by my illustrious Princes, whose honour is defended by a public oath.
Source: Memorial of Symmachus (New Advent)