(2). The faculty which preserves the perceptions of the Common Sense--images and not ideas like the memory. The judgment that whiteness and sweetness exist in the same thing is completed by this faculty; since, if it does not preserve the image of the subject, Common Sense cannot perceive the predicate. (3). The power which perceives individual ideas. The sheep thinks of the enmity of the wolf, and runs away from him. Some forms of life lack this power, e.g. the moth which hurls itself against the candle-flame. (4). Memory--the preserver of ideas. (5). The power of combining images and ideas, e.g. the winged man. When this faculty works under the guidance of the power which perceives individual ideas, it is called Imagination; when it works under the control of Intellect, it is called Conception. But it is the spirit which distinguishes man from other animals. This essence of humanity is a "unity", not oneness. It perceives the Universal by itself, and the particular through the external and the internal senses. It is the shadow of the Absolute Light, and like it manifests itself in various ways--comprehending multiplicity in its unity. There is no necessary relation between the spirit and the body. The former is non-temporal and non-spatial; hence it is changeless, and has the power of judging the visible multiplicity. In sleep the spirit uses the "ideal body" which functions like the physical body; in waking life it uses the ordinary physical body. It follows, therefore, that the spirit stands in need of neither, and uses both at will. Hādī does not follow Plato in his doctrine of transmigration, the different forms of which he refutes at length. The spirit to him is immortal, and reaches its original home--Absolute Light--by the gradual perfection of its faculties. The various stages of the development of reason are as follows:-- A. Theoretical or Pure Reason-- 1{st} Potential Reason. 2{nd} Perception of self-evident propositions. 3{rd} Actual Reason. 4{th} Perception of Universal concepts. B. Practical Reason-- 1{st} External Purification. 2{nd} Internal Purification. 3{rd} Formation of virtuous habits. 4{th} Union with God. Thus the spirit rises higher and higher in the scale of being, and finally shares in the eternity of the Absolute Light by losing itself in its universality. "In itself non-existent, but existent in the eternal Friend: how wonderful that it _is_ and _is not_ at the same time". But is the spirit free to choose its course? Hādī criticises the Rationalists for their setting up man as an independent creator of evil, and accuses them of what he calls "veiled dualism". He holds that every object has two sides--"bright" side, and "dark" side. Things are combinations of light and darkness. All good flows from the side of light; evil proceeds from darkness. Man, therefore, is both free and determined.