12 December -- St Finnian of Clonard

 'The Master of the Saints of Ireland', Finnian is known as a great teacher - Ciarán of Clonmacnoise and Colmcille of Iona are among the many to have trained under him. They and others have taken seeds of knowledge from Finnian's monastery at Clonard, and planted them abroad with great success. As might be expected from such a renowned teacher, Finnian has invested much of his life in his own education. France and Britain have been formative training grounds for him, and have had a direct bearing on the values and culture of his foundation at Clonard. In itself, this is far from unusual, as schooling in foreign lands is the norm for early Christian teachers such as Finnian.

More here on one  of the more well-known of ancient Ireland's saints.  He's pretty much eclipsed in this country by Our Lady of Guadalupe's great feast on the 12th.  But he's still on the Irish calendar.