Of these the Olympic festival is the oldest, at any rate as regards its national importance. The festival and the games celebrated there existed long before the year 776 B.C., after which its regular recurrence was used for expressing the date of the year; still, it is only from this time onward that we can regard it as a really national festival. The Pythians did not begin to calculate by their games till the year 586, the Isthmians in 582, and the Nemeans in 573. The Olympic and Pythian festivals recurred every four years, the other two every two years; the Olympic festivals always took place at the first full moon of the summer solstice, the Pythian in the autumn of the third year of an Olympiad; we cannot determine the exact period of the others, and only know that the Isthmian games were held at midsummer, and the Nemean alternately in winter and in summer. The main features of all, next to the usual acts of worship, such as prayer, sacrifices, etc., was the gymnastic contests connected with them. All four had attained so great a reputation even beyond the frontiers of their narrow home that most of the Greek states took part in them by means of official embassies ([Greek: theôriai]) and numbers of spectators came from a distance, and a great market was held there in consequence. This universal interest taken in the festivals gave them a character of inviolability, so that they were able to continue even in time of war, since there was always a truce as long as the games lasted, and all who took part in them were allowed to travel undisturbed, as soon as the heralds of peace had announced the beginning of the sacred month, first in their own state, and afterwards in that of all the Greeks who took part in the contests. We possess far more details concerning the Olympic festival than any other, and, in fact, it exceeded them all in importance. The games constituted the most important part, and it was for their sake that spectators came from most distant parts of the ancient world to the plain of the Alpheus; and, indeed, the myth concerning the origin of the festival is intimately connected with these games. Every free-born Greek was allowed to take part in them. Barbarians were strictly rejected, at any rate in the best period of the Olympic festival, and it was not till the time of the Roman Empire, when its glory had long departed, that this practice was abandoned. They also excluded all who had committed murder or any other great crime, or forfeited the rights of citizenship, and before the beginning of the contest a strict examination was held into the claims of all who desired to take part. At first only youths and men were admitted; from 632 onwards boys were allowed to contend, at any rate in some of the sports. We hear of women taking part or being victors in the Olympic games, but this does not mean that they appeared in person; in the chariot races and riding it was not the custom for the owner of a horse to drive or ride, and thus rich women who were interested in the training of horses could let them run at the Olympic games; and since it was not the charioteer or rider, but the trainer and owner of the horses who was crowned, they might thus obtain the prize.