In any functional psychosis an offhand diagnosis is dangerous. When one deals with such a condition as stupor, however, the problem is exacting, for, although “stupor” may be seen at a glance, what is seen is really only a symptom or a few symptoms. “Stupor,” then, is more of a descriptive than a diagnostic term. The real problem is to determine the psychiatric group into which the case should be placed. This is a difficult task, for the differential diagnosis rests on the observation and utilization of minute and unobtrusive details. A correct interpretation can be only reached by obtaining a complete history of the onset and observing the behavior and speech of the patient for a long period, usually of weeks, sometimes of months. With these precautionary words in mind, it may be well to summarize briefly the diagnostic problems in connection with benign stupor. In the first place one naturally considers the differentiation from conditions of organic stupor or coma. Since psychotic stupors never develop without some signs of mental abnormality, the history is usually a sufficient basis for final judgment. In case no anamnesis is obtainable the functional nature of the trouble may be recognized by the absence of those physical signs which characterize the organic stupors. One sees no violent changes in respiration, pulse or blood-pressure, such as are present in the intoxication comas of diabetes or nephritis. There is no characteristic odor to the breath, and the urine is relatively normal. The unconsciousness of trauma or apoplexy is accompanied by focal neurological signs. Even in aerial concussion (so frequently seen in the war) where no one part of the brain is demonstrably affected more than another, there are neurological evidences of what one might call “physiological” unconsciousness. The eyes roll independently, the pupils fail to react to light. On the other hand, there are definite symptoms characteristic of the functional state. Mental activity is evidenced by a muscular resistiveness or retention of urine. Even in states of complete relaxation the eyes move in unison, the pupils react to light, and almost universally the corneal reflex is present. The patient appears in a deep sleep rather than actually unconscious. The post-epileptic sleep may resemble a stupor strongly. But this condition is temporary and the situation and appearance of the patient betrays the fact that he has just had a convulsion. Rarely, protracted stuporous states occur in epilepsy which closely resemble the conditions described in this book. In fact it is probable the true stupors may occur in epilepsy just as in dementia præcox or manic-depressive insanity.