In the days after the crucifixion of Jesus, the apostles gathered together. It was decided that one should be chosen from among the disciples to replace Judas as a member of the twelve. Two names were chosen. Joseph called Barsabas and Matthias who were both disciples numbered among the first 70 who was with Jesus since His baptism. Lots were cast and Matthias was chosen. The orginization of the Church was kept intact and spread out from this point.
Matthias' name comes from the Hebrew "gift of YHWH (the name of God)." All the information after his election comes from tradion and legend. Sometimes contradictory and vague, we hear stories of Matthias traveling to Northern Africa in Ethiopia after preaching in Judea. Legend says that in 80 AD he was either crucified there in Africa or was stoned and then beheaded in Jerusalem. Another legend says that St. Helena, mother of Constantine brought back his relics to Rome from Jerusalem. This may be his relics or another bishop named Matthias from the year 120 AD.
Matthias preached the need for mortification of the flesh with reguard to its senual and irregular desires. He said, "we must combat our flesh, set no value upon it, and concede to it nothing that can flatter it, but rather increase the growth of our soul by faith and knowledge". We get this from the apochrophal Gospel of Matthias which has strong Gnostic and heretical tones, yet played off of the martyrs conviction for people to keep themselves under control.
On Thursday May 14th, we celebrate the feast day of St. Matthias the Apostle who was elected and subsequently martyred preaching the Gospel.