Edit: it's also sometimes the feast of St. John Chrysostom, in the Byzantine Rite.
Here's a Sermon on the importance of obedience.
How refreshing it is to hear a priest who talks about the Gospel of St. John, and not the "Johannine Gospel" like we're at an undergraduate bible class at a Liberal University like Creighton.
It's also interesting to note that the way he's talking seems to indicate that there are a good number of young people at Divine Liturgy.
True authority comes from service.