“The states of consciousness are all that psychology needs to do her work with. Metaphysics or theology may prove the Soul to exist; but for psychology the hypothesis of such a substantial principle of unity is superfluous.” NeedsMaySoulStatesConsciousnessPrinciplesPsychologyProveUnityTheologyMetaphysicsHypothesisSuperfluousStates Of Consciousness Book:Psychology, Briefer Course Source: Psychology, Briefer Course