The value does not depend merely on historical causes; its chief importance lies in the fact that it has a meaning for the actual present, and for the future, in their psychological aspects. For to the Zürich School the symbol is not merely a sign of something repressed and concealed, but is at the same time an attempt to comprehend and to point out the way of the further psychological development of the individual. Thus we add a prospective import to the retrospective value of the symbol. The method of the Zürich School is therefore not only analytical and causal, but also synthetic and prospective, in recognition that the human mind is characterised by "causæ" and also by "fines" (aims). The latter fact needs particular emphasis, because there are two types of psychology, the one following the principle of hedonism, and the other following the principle of power. Scientific materialism is pertinent to the former type, and the philosophy of Nietzsche to the latter. The principle of the Freudian theory is hedonism, while that of Adler (one of Freud's earliest personal pupils) is founded upon the principle of power. The Zürich School, recognising the existence of these two types (also remarked by the late Professor William James), considers that the views of Freud and Adler are one-sided, and only valid within the limits of their corresponding type. Both principles exist within every individual, but not in equal proportions. Thus, it is obvious that each psychological symbol has two aspects, and should be interpreted according to the two principles. Freud and Adler interpret in the analytical and causal way, reducing to the infantile and primitive. Thus with Freud the conception of the "aim" is the fulfilment of desire, with Adler it is the usurpation of power. Both authors take the standpoint in their practical analytical work which brings to view only infantile and gross egoistic aims. The Zürich School is convinced of the fact that within the limits of a diseased mental attitude the psychology is such as Freud and Adler describe. It is, indeed, just on account of such impossible and childish psychology that the individual is in a state of inward dissociation and hence neurotic. The Zürich School, therefore, in agreement with them so far, also reduces the psychological symbol (the phantasy products of the patient) to the fundamental infantile hedonism, or to the infantile desire for power. But Freud and Adler content themselves with the result of mere reduction, according to their scientific biologism and naturalism.