The one physical uniformity of mortals is the brain and nervous system; nevertheless, there are three basic organizations of the brain mechanism: the one-, the two-, and the three-brained types. Urantians are of the two-brained type, somewhat more imaginative, adventurous, and philosophical than the one-brained mortals but somewhat less spiritual, ethical, and worshipful than the three-brained orders. The reading encompassed Paper 49:5.13-32, p. 566