St. Casimir, Confessor
St. Casimir, son of Casimir IV, king of Poland, and of Elizabeth of Austria, practised the most sublime virtues amid all the danger of the Court (Collect). He continually meditated on the Passion of Jesus, which inspired him with a great love for corporal mortification and for the poor, those suffering members of Christ. The abundant alms (Epistle) which he distributed made him to be called "the father and defender of the poor and unfortunate". Always ready for the coming of the Lord (Gospel), he foretold the day of his death, which happened on March 4th, 1483.
Imitating the fortitude and constancy of St. Casimir, let us unite ourselves to the Saviour who atones for our sins and let us despise worldly goods and desire heavenly treasures (Collect).
Os justi meditabitur sapientiam, et lingua ejus loquetur judicium; lex Dei ejus in corde ipsius. * Noli aemulari in malignantibus: neque zelaveris facientes iniquitatem.
The mouth of the just shall meditate wisdom, and his tongue shall speak judgement: the law of his God is in his heart. * Be not emulous of evildoers: nor envy them that work iniquity.
(Psalm 36:30-31,1 from the Introit of Mass)
Deus, qui inter regales delicias, et mundi illecebras sanctum Casimirum virtute constantiae roborasti: quaesumus: ut ejus intercessione fideles tui terrena despiciant, et ad caelestia semper aspirent.
O God, who amidst the delights of royalty and the blandishments of the world, didst strengthen holy Casimir with the virtue of constancy, grant, we beseech Thee, that by his intercession Thy faithful may despise earthly things, and ever aspire to those of heaven.
From the Catholic Encyclopaedia: http://www.newadvent.org/cathen/03402a.htm