But here a very important question arises. Can man obey the fundamental and primitive impulses of his nature without gravely injuring himself or his fellow beings? He cannot assert either his sexual desire or his desire for power unlimitedly, and the limits are moreover very restricted. The Zürich School has in view also the final result of analysis, and regards the fundamental thoughts and impulses of the unconscious, as symbols, indicative of a definite line of future development. We must admit there is, however, _no scientific justification_ for such a procedure, because our present-day science is based as a whole upon causality. But causality is only one principle, and psychology essentially cannot be exhausted by causal methods only, because the mind lives by aims as well. Besides this disputable philosophical argument, we have another of much greater value in favour of our hypothesis, namely, that of _vital necessity_. It is impossible to live according to the intimations of infantile hedonism, or according to a childish desire for power. If these are to be retained they must be taken symbolically. Out of the symbolic application of infantile trends, an attitude evolves which may be termed philosophic or religious, and these terms characterise sufficiently the lines of further development of the individual. The individual is not only an established and unchangeable complex of psychological facts, but also an extremely changeable entity. By exclusive reduction to causes, the primitive trends of a personality are reinforced; this is only helpful when at the same time these primitive tendencies are balanced by recognition of their symbolic value. Analysis and reduction lead to causal truth; this by itself does not help living, but brings about resignation and hopelessness. On the other hand, the recognition of the intrinsic value of a symbol leads to constructive truth and helps us to live. It induces hopefulness and furthers the possibility of future development. The functional importance of the symbol is clearly shown in the history of civilisation. For thousands of years the religious symbol proved a most efficacious means in the moral education of mankind. Only a prejudiced mind could deny such an obvious fact. Concrete values cannot take the place of the symbol; only new and more efficient symbols can be substituted for those that are antiquated and outworn, such as have lost their efficacy through the progress of intellectual analysis and understanding. The further development of mankind can only be brought about by means of symbols which represent something far in advance of himself, and whose intellectual meanings cannot yet be grasped entirely. The individual unconscious produces such symbols, and they are of the greatest possible value in the moral development of the personality.