The Three Holy Hierarchs is Feast Day and a holiday in Greece that celebrates the patron saints of education: Basil the Great, John Chrysostom, and Gregory the Theologian. These three men are venerated as saints not only in Catholicism but also in Eastern Orthodoxy, Anglicanism, and other Christian denominations. 

During the 11th century, a debate raged in Christian churches over which of the three hierarchs were indeed the greatest ones. Some people believed it was Saint Basil, while other people were firmly in the corner of John Chrysostom. Each of these saints had their own Feast Day in January—with St. Basil having his on January 1st; Saint Gregory on January 25th; and John Chrysostom on January 27th. The Eastern Churches declared that each was equal before God. That’s when all three Feast Days were pushed together and celebrated on January 30th.