 When a dog or a snake sacrifices one of its members in order to save its head or sacrifices some part in order to save the whole, then it prefers the whole over the part and the head over the other member. Therefore, these animals must have some common power which shows both extremes simultaneously, their mutual comparison, and the preference of one over the other—although it does not do this with the same fullness and degree of reflexive judgement as does the intellect. (Summa II q. 62, p. 588)