The relation between Proclus and Plotinus requires to be carefully noted. The effect of Aristotle's teaching is seen in the argument that movement requires three terms : the First Cause as that which is itself unmoved but pro­ duces all m otion; the intermediary which both moves and is moved ; and, thirdly, that which is only subject to motion, the passive and inert substance. The soul belongs to the second type, for it has a principle of self-movement and is thus at once related by likeness to that which is superior to it, while it remains inferior to the First Cause because it is subject to motion. The peculiarity of the soul is its power of self-movement, which means its power of reflection. The self-movement is described as the power of turning back upon the self, and that is a power which belongs only to the incorporeal and is, in fact, nothing more than the idea of self-consciousness or reflection trans­ lated into terms of motion in order to give it a cosmic significance. The Aristotelian element in Proclus results in a separation of the One from that which the One pro­ duces. God therefore remains transcendent as a remote cause, not being identified with the immanent cause of motion in derivative beings. So in spite of much fanciful elaboration we have little more in this system than a re­ statement of Aristotle's teaching. For the soul is primarily a principle of motion, as in Plato and Aristotle ; it is con­ stituted by the power of thought and is what it thinks ; it is therefore immaterial in the sense that thoughts are

immaterial ; its activity proves if to be an independent reality ; and, if we add to this the idea of separate exist­ ence, it may become a transcendent reality destined to live and move in transcendent regions of Being where there is neither space nor time. A doctrine so elaborate and so bold in its flights of constructive imagination was naturally destined to attract in all ages those who had the tempera­ mental bias toward mysticism and aimed to construct some ontology of the intellect. For all work of that kind Proclus becomes the archetype. The importance of Proclus may be summarized under the following heads : he restated the doctrines of Plotinus in a manner eminently character­ istic of his times (411-485 B.C.) : he gives the functions of consciousness a peculiar place between matter and the transcendental forms of Being, a doctrine which later becomes a traditional dogma : he attempts to formulate a concept of consciousness, after the manner of Plotinus. Though the modern psychologist finds little occasion to quote Proclus, this last phase of ancient thought has influenced some modern writers. Hegel, as we know from his letters, felt a growing admiration for this writer, though it is doubtful whether that fact will enhance the reputation of either so far as psychology is concerned. It is inter­ esting, however, to ask ourselves whether humanity has quite outgrown the doctrine that the food of the soul is truth. Is there any profound advance in many other forms of this doctrine of “ assimilation ” ? Are we any better off if we can solemnly endorse the statement that the “ food of the soul ” is phosphorus, or that it lives on " blood ” ? B y touching these extremes thought finds its limits.1