The birth of a child is an act of nature, an act generally performed as satisfactorily as any other bodily function. Birth has, however, so deep a meaning for the mother, as well as for her family and her friends, and is, above all, so vital to the future of the race, that it has naturally become the subject of many impressive superstitions. Primitive peoples have invariably embodied in their religion their views of the origin of life and the phenomena of its inception. With these mysteries Greek and Roman mythology dealt extensively, as did also the myths of the Phoenicians, the Egyptians, the Chinese, and the people of ancient India. No race, indeed, has lacked its own interpretation of childbirth, and no phase of the process has failed to have attributed to it a supernatural significance. A number of these superstitions still distress women on the eve of motherhood. To correct exaggerations and to deny many utterly false impressions of childbirth there is no better way than to give a frank account of what does actually occur. I shall adhere to a purely physiological description of the event, for, although I appreciate fully the fact that its sociological and sentimental aspects are perhaps equally important, these are not, in my opinion, pertinent to a medical discussion. In a scientific sense the act of birth may be described as a series of muscular contractions which widen the birth-canal and expel the contents of the pregnant womb. Since the process requires an expenditure of energy, it has come to be called labor. Intrinsically, labor does not differ from many other physiological acts. The heart drives blood into the arteries; the bladder empties itself; the intestine moves its contents and finally expels the undigested residue. All these acts strongly resemble that of birth; but they also differ from it, for the head of the fetus is a hard body which resists being molded to the shape of the passageway through which it enters the world. To this resistance the pain which accompanies delivery is largely due. And yet even in this respect the act of birth is not unique; certain circumstances lead to painful contractions of the muscle fibers in the intestine and less frequently of those in other organs.