As regards sacerdotal medicine, it was principally derived from the false ideas prevalent among primitive peoples about the causes of maladies. When, for example, an individual in full health was seized with sudden illness, no one could imagine, in those times of profound ignorance, that this happened in a natural manner; the fact was therefore attributed to a supernatural cause, that is, to his having been stricken by the wrath of some divinity. In this state of things it was believed to be absolutely necessary to propitiate the inimical or vengeful divinity, so that the patient might be restored to health. It was, therefore, very natural that the intervention of sacerdotal aid should be sought, that is, of the supposed intermediaries between human beings and the gods. The priests, on their side, were ready to occupy themselves with such cases, for their services were always well recompensed, and, added to this, if the patient recovered, the respect and veneration of the people for the sacerdotal caste was considerably increased, whilst if he did not, this simply meant that he or his family was not worthy of receiving the desired pardon, or that, anyhow, the Divinity, for good reasons of his own, would not grant it. However, it being to the interest of the priests to obtain the greatest possible number of cures, they did not limit themselves merely to offering up prayers and sacrifices and to imposing on the patients the purification of themselves and other religious exercises; they also put into practice—always to the accompaniment of ritualistic words and ceremonies—the means of cure which their own experience and that of others suggested to them. The art of healing the sick was transmitted from generation to generation in the sacerdotal caste, acquiring an ever greater development and complexity in proportion to the making of new observations and fresh experiences. It is to be understood that in this manner the priests became more and more skilful in the treatment of disease; they were really the doctors of those times, albeit their curative practices were mixed up with an ample dose of imposture. This, at least in many cases, must have had, besides, the advantage of acting favorably on the patients by means of suggestion. We learn from Herodotus that the Babylonians used to carry the sick into the public squares; the passers-by were expected to make inquiries as to their illnesses, and if it so happened that they or any of their acquaintances had been similarly afflicted, to come to the aid of the patient by offering their advice and making known the means of treatment that had effected recovery, exhorting him, at the same time, to have recourse to them. This usage had without doubt its advantages, as it must have led, little by little, to the recognition of such remedies as were most efficacious, among all those recommended, against the various maladies.