distinguishes one body from another—for example, that the celestial sphere occupies a spatial location because it is a celestial sphere, water because it is water, and air because it is air—then this is false, and no rational person would maintain it. All bodies share the property of occupying a spatial location and lying in a direction, and a property universally shared by them can only be due to that which distinguishes some of them from others. For if it were due to what distinguishes some of them from others, it would have to be confined to some of them, like all other properties necessarily bound up with particular distinguishing attributes.
If it is said that different things may share a general, necessary attribute, as different species of animals share the quality of being animals, this is correct. Yet the property they all share cannot be due to what is particular to each animal.
If it is said that a ruling of the same kind may be grounded in two different causes—as the permissibility of shedding blood is grounded in apostasy, killing, and adultery; ownership in inheritance, sale, and hunting; and the obligation to perform the full ritual bath in ejaculation, penetration, and menstruation—then the obligation established by one cause is not the very same obligation established by another, but its counterpart. Moreover, the two differ according to their causes. Ownership established through inheritance is not identical in every respect to ownership established through sale; rather, it has distinctive characteristics. Likewise, the permissibility of shedding blood established on account of apostasy is not identical to that established on account of killing; there are specific differences between them.
Similarly, the ritual bath prescribed on account of menstruation differs in some respects from that prescribed on account of penetration. Ejaculation and penetration, however, are of a single kind.
As for what reason conclusively establishes as belonging to the common element, it must be attributed to an element