The cures which took place later on in the sanctuaries of Aesculapius by means of incubation, or temple sleep, which were customary even in the Roman period, were of a different nature. The invalids were not actually cured during their sleep, but they received in a dream an indication from the god of the manner in which they could be freed from their sufferings, directions sometimes in reference to dietetic measures, such as baths, fasting, etc., and sometimes to medicines. In these cases, too, we must suppose that the invalid fell into a state of half-sleep, during which a priest in the form of the god appeared, and gave the directions in question, for which a quantity of medical knowledge, gradually acquired by experience, stood the priests in good stead. Sometimes healing _thermae_, or springs, which were found near some of the sanctuaries, did good service, especially if the invalids remained there for some time. The Greek sanctuaries of Aesculapius were almost always situated on high ground, where the air was healthy and pure. There must always have been houses for the reception of sick people, especially those who came from a great distance. Thus the sanctuary of Aesculapius at Epidaurus was about four miles from the town, but, to prevent any pollution of the holy place, no children must be born there and no one must die there, and on this account pregnant women and dying people were mercilessly sent away. Of course the priests did not give their aid for nothing, but were repaid in money or offerings to the shrine, and we find many allusions to these offerings; indeed, the sanctuary at Epidaurus could vie in wealth with that at Delphi. It was not only in the temples of Aesculapius that dream oracles existed. Many other gods or heroes took similar care for suffering humanity, just as at the present day the shrines which possess miraculous pictures of Madonnas or relics vie with one another. Thus sick people were received in the temple of Hades, situated between Tralles and Nysa, in Lydia, but here it was the priests and not the patients to whom the method of cure was revealed in sleep, and this was also the case in the temple of Amphiaraus at Oropus, on the borders of Attica and Boeotia. Mention must also be made of quackery and sympathetic cures. The belief in the latter was very general in antiquity, and was shared even by unprejudiced men of considerable education. This was effected by amulets, supposed to ward off or heal diseases, and also by magic words which we should now describe as conjuring; laying on of hands, symbolical washing, etc. The sellers of drugs were specially occupied with quackery; besides rouge, paint, and other means of promoting beauty, they also sold medicines and offered their wares in mountebank fashion. Very often, when sick people had failed to obtain alleviation or cure from a regular physician, they gave him up and resorted to quackery instead.