The term nostalgia is derived from two Greek words, signifying, in our vernacular, home-sickness. The derivation of the word indicates the pathology. It is a mental disorder, and belongs to the class melancholia. Certain physical symptoms precede, accompany, or follow the development of the mental aberration: heat of head; increased rapidity of the circulation; constipation; gastro-intestinal disorders of various kinds; a low febrile state simulating typhoid. The mental despondency and the exaltation of the imaginative faculty increase with the decline in the physical strength. Weeping, sighing, groaning, and a constant yearning for home; hallucinations and sometimes maniacal delirium, are the particular forms in which the disorder of the brain expresses itself.

Does the mental state precede the development of the physical symptoms? Is this sufficient of itself to produce that train of gastro-intestinal disorders and febrile phenomena which characterize the progress of the case? My own experience leads me to the conclusion that derangement of the health, particularly of the primary assimilation, leads to the disorders of intellect, and that in those cases in which the affection of the mind precedes the physical disorders, there is much reason to suspect a predisposition to mental derangement to have existed. These questions are not without interest in view of the causes and degree of prevalence of nostalgia during the war.