Today we celebrate the Feast of St. Mark the Evangelist. From the Collect (Roman Missal, 3rd edition):
O God, who raised up Saint Mark, your Evangelist, and endowed him with the grace to preach the Gospel, grant, we pray, that we may so profit from his teaching as to follow faithfully in the footsteps of Christ. Who lives and reigns with you in the unity of the Holy Spirit, one God, for ever and ever.
For more information on St. Mark and his feast day, visit: https://www.catholicculture.org/culture/liturgicalyear/calendar/day.cfm?date=2018-04-25