Casimir was the second son of King Casimir IV and Elizabeth of Austria. Casimir made the decision to commit his life to God at an early age, despite pressure and ridicule from his family. Casimir found the luxuries around him to be only temptations away from the true royalty of God. He resolved to live his life in simplicity, and follow the way of Christ. Casimir died at the young age of 23 from lung disease. His feast day is celebrated on March 4th.