In the organization of our military forces in 1917, when this country entered the war, every effort was made to take advantage of the experience of others. Of the men returned to Canada from European battlefields on account of disability, the nervous and mental cases contributed ten per cent of the total at that time, as was shown by Farrar.[90] These were distributed as follows:—neurotic reactions, fifty-eight per cent; mental disease and defect, sixteen per cent; head injuries, fourteen per cent; epilepsy and epileptoid conditions, eight per cent; and organic diseases of the central nervous system, four per cent. The first group mentioned consisted of neuroses in general and included the so-called cases of "shell shock," which brings us to one of the most interesting problems of the war. Dean A. Worcester, in a recent letter to the editor of _Science_, has raised the question as to whether this is a new disease. He calls attention to the following reference by Herodotus to the Battle of Marathon which occurred in the year 490 B.C.:—"The following prodigy occurred there: An Athenian, Epizelius, son of Capliagoras, while fighting in the medley, and behaving valiantly, was deprived of sight, though wounded in no part of his body, nor struck from a distance; and he continued to be blind from that time for the remainder of his life. I have heard that he used to give the following account of his loss. He thought that a large, heavy armed man stood before him, whose beard shaded the whole of his shield; that this specter passed by him, and killed the man that stood by his side. Such is the account I have been informed Epizelius used to give."