scientific knowledge which does not explain a fact by causes and principles; and metaphysics, or the final explanation, is an expression of the same scientific spirit, and proceeds by the same method. Knowledge is an organic system, and consists of a double rhythm which goes from facts to theory, from problem to answer, from the concrete to the abstract, in order to return from the abstract to the concrete, from the theory to the new facts which it suggests. Knowing is a living process, like life itself. Knowledge cannot be explained by entities, neither can life be understood by such conceptions as vitalism, mechanical action, or animism. Life consists of an ensemble of functions executed by means of organs. The function is the unity whose two terms are inner and outer, organ and external agent, which are in interaction, and neither is merely passive, but both are active as well. Every function is the exercise of mind on the occasion of an external stimulus which in turn is determined by the constitution of the organ and of the external agent. In the emotional activities, as in those of sense, every function is produced by the action of the physical world on the nervous system. Every function is, therefore, in its real nature an absolutely original activity of the mind, which requires for its actualization an external stimulus and a peripheral organ. This is not a mechanical account of man, but it reduces all his actions to a primitive mental activity; and therefore, directly or indirectly, the brain or the mind is in continuous relation with all the vegetative functions of the body, not only to perceive the stimuli which are received, but also to react on those stimuli. Thought is bound up with all the functions of organic life.—In order to explain the apparent difference between mental action and the normal activities of vegetative life, the author accepts the theory of polyzoism or polypsychism, a plurality of psychic centres, on the analogy of the brain and nervous system; and just as the brain and the other ganglionic centres are physiologically united, so the different psychic centres form a unity. The function of the lower and higher centres is always the same, and they differ only in complexity and intensity. In support of this he mentions hypnotism, and concludes that facts and logic alike show that mind and body form one ideal unity.
The doctrine that knowing consists in perceiving the resemblances and differences between things, though long held, has been supplemented by a third relation equally fundamental. This is the relation of opposition. Aristotle based his ethical theory on this category. Virtue is the habit of choosing the mean between two opposites or extremes. In natural phenomena this relation appears in the form of rhythm, evolution and dissolution. It is probable that this idea came into consciousness through the study of history, and reflection on the contests which men had to undergo in the
