Know ye not... — The illustration which follows refers to these Isthmian games (so called from their taking place in the isthmus where Corinth stood) with which his readers would be familiar. These, like the other games of Greece — the Olympian, Pythian, and Nemean — included every form of athletic exercise, and stood on an entirely different footing from anything of the kind in modern times. For the Greek, these contests were great national and religious festivals. None but freemen could enter the lists, and they only after they had satisfied the appointed officers that they had for ten months undergone the necessary preliminary training. For thirty days previous to the contest the candidates had to attend the exercises at the gymnasium, and only after the fulfilment of these conditions were they allowed, when the time arrived, to contend in the sight of assembled Greece. Proclamation was made of the name and country of each competitor by a herald. The victor was crowned with a garland of pine leaves or ivy. The family of the conqueror was honoured by his victory, and when he returned to his native town he would enter it through a breach in the walls, the object of this being to symbolise that for a town which was honoured with such a citizen no walls of defence were needful (Plutarch). Pindar, or some other great poet, would immortalise the victorious hero’s name in his verse, and in all future festivals the foremost seats would be occupied by the heroes of former contests.
So run — i.e., run in the way referred to, so that you may gain a prize.