Anyone of you who makes the necessary effort to look up this question will certainly be strongly impressed by the wealth of evidential material. But he will also meet with a difficulty. The meaning of a symptom lies, as we have seen, in its connection with the life of the patient. The more individually the symptom has been formed, the more clearly may we expect to establish this connection. Then the task resolves itself specifically into a discovery, for every nonsensical idea and every useless action, of the past situation in which the idea was justified and the action served a useful purpose. The obsessive act of the patient who ran to the table and rang for the maid is a perfect model of this kind of symptom. But symptoms of quite a different type are very frequently seen. They are what we call _typical_ symptoms of a disease, in each case they are practically identical, the individual differences in them vanish or at least fade away, so that it is difficult to connect them with the patient’s life or to relate them to special situations in his past. Let us consider the obsessional neurosis again. The second patient’s ceremonies preparatory to sleep are in many ways quite typical, although showing enough individual features as well to make an “historical” interpretation, so to speak, possible. But all obsessional patients are given to repetitions, to isolating certain of their actions and to rhythmic performances. Most of them wash too much. Those patients who suffer from agoraphobia (topophobia, fear of space), no longer reckoned as an obsessional neurosis but now classified as anxiety-hysteria, reproduce the same features of the pathological picture often with fatiguing monotony. They fear enclosed spaces, wide, open squares, long stretches of road, and avenues; they feel protected if accompanied, or if a vehicle drives behind them, and so on. Nevertheless, on this groundwork of similarity the various patients construct individual conditions of their own, moods, one might call them, which directly contrast with other cases. One fears narrow streets only, another wide streets only, one can walk only when few people are about, others only when surrounded with people. Similarly in hysteria, beside the wealth of individual features there are always plenty of common typical symptoms which appear to resist an easy interpretation on historical lines. Do not let us forget that it is these typical symptoms which enable us to take our bearings in forming a diagnosis. Supposing we do trace back a typical symptom in a case of hysteria to an experience or to a chain of similar experiences (for instance, an hysterical vomiting to a series of impressions of a disgusting nature), it will be confusing to discover in another case of vomiting an entirely dissimilar series of apparently causative experiences. It almost looks as though hysterical patients must vomit, for some unknown reason, and