No conclusions are intended to be drawn in these introductory pages. Such conclusions as are risked are placed in the Epicrisis (see Section E). But so much can be said: If we are ever to surround the problem of Shell-shock (_intra bellum_ or _post bellum_), we must approach it with no artificial and _à priori_ limitations of its scope. We must not even agree beforehand that Shell-shock is nothing but psychoneurosis: that would be a deductive decision unworthy of modern science. In the collection of these cases, I have tried to place the topic upon the broadest clinical base. Samples of virtually every sort of mental disease and of several sorts of nervous disease have been laid down, some obviously not instances of Shell-shock, some mixed with clinical phenomena of Shell-shock, others hard to tell offhand from Shell-shock--the whole on the basis that we shall earliest learn what Shell-shock, the pathological event, is by studying what it is not. As the sequel may show, we are perhaps not entitled to regard Shell-shock, the pathological event, as always associated with shell-shock, the physical event. We shall, therefore, find in Section A (see tables on pages 6 and 7). (1) Cases without either physical shell-shock, or pathological Shell-shock--psychoses of various kinds incidental in the war (--+). (2) Cases with physical shell-shock but without pathological Shell-shock--psychoses of various kinds seemingly liberated by, aggravated by, or accelerated by the physical factor of shell-shock (+-+). (3) Cases without physical shell-shock but with both symptoms of pathological Shell-shock as well as of other psychosis (-++). (4) Cases with physical shell-shock, with clinical phenomena of Shell-shock, as well as of other psychosis (+++). At the end of Section A, accordingly, we shall be left with two more formulae for discussion in Sections B, C, and D, viz: (5) Cases without physical shell-shock but with symptoms of pathological Shell-shock (-+-). (6) Cases with physical shell-shock and pathological Shell-shock (++-). The data of Section A will solidly prove that Shell-shock, however picturesque the term for laymen or in the _argot_ of the clinic, is medically most intriguing. As we cannot get rid of the term (even by suppressing it in parentheses or by condemning it to the limbo of the _so-called_), we must make the best of it by calling Shell-shock just the ore in the clinical mine. To say the least, the _term_ is harmless: it merely stimulates the lay hearer to questions. These questions he must ask of the expert. But every time that the expert suavely states that Shell-shock is nothing but psychoneurosis, that expert runs the risk of hurting some patient who may or not have a psychoneurosis but has been _called_ psychoneurotic. All the while, of course, the suave expert is perfectly right--_statistically_. In fine, the man you have called a victim of Shell-shock is probably a victim of psychoneurosis, _but only probably_!