17. The very form of thy body and the uses of thy limbs teach thee this. Can one limb claim the duties of another? Can the eye claim for itself the duties of the ear; or the mouth the duties of the eye; or the hand the service of the feet; or the feet that of the hands? Nay, the hands themselves, both left and right, have different duties to do, so that if one were to change the use of either, one would act contrary to nature. We should have to lay aside the whole man before we could change the service of the various members: as if, for instance, we were to try to take food with the left hand, or to perform the duties of the left hand with the right, so as to remove the remains of food—unless, of course, need demanded it.