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TRANSLATOR'S PREFACE.
sine qua non in the treatment. It is only by following Freud in this manner that one can hope to solve the hitherto unsolved riddles of the psychoneuroses and psychoses.
This treatment is more difficult than one can describe in a preface. It not only presupposes a thorough knowledge of Freud but an equal knowledge of normal and abnormal psychology. Those who have not acquired this knowledge by reason of time or otherwise may remember the words of the younger Pliny: Ut enim de pictore scalptore fictore nisi artifex indicare, ita nisi sapiens non potest perspicere sapientem.
A. A. Brill.
