a fine house on a usurped foundation. When the foundation’s owner came, contested his right to it, and tore it out, the house collapsed.”

Such are the extensive subsidiary rulings set out in the Book of Oaths, which their deviser based on what he believed to be the position of the Kufan grammarians. The fundamental principle governing oaths is to refer first to the oath-taker’s intention and purpose, then to the circumstantial indications of his intent, such as the occasion of the oath and what prompted it, and then to his customary usage, whether or not it accords with the Arabic language. For oaths and all other forms of communication between people—in transactions, correspondence, writings, and elsewhere—share a common feature: the wording indicates the speaker’s intention and meaning. This varies with languages and customs.

What the wording indicates also varies according to the circumstantial and verbal context. Moreover, a person’s intention need only be inferred when it is unknown. If we can [know] his intention with certainty, we have no need to resort to uncertainty. In some matters, however, a speaker’s claim to have intended something contrary to the apparent meaning is not accepted, as when other people’s rights are involved, such as in admissions and similar statements. This is established in its proper place; the purpose here is merely to illustrate the point.

Since this is the fundamental principle governing oaths, the person devising those subsidiary rulings may be told: “If this is the basis of his intention, which in most cases conflicts with the implications of what you have stated by way of