St. Andrew, the elder brother of St. Peter, and like him, a fisherman of the lake of Galilee, on hearing St. John the Baptist proclaim that Jesus was the Lamb of God, was moved to follow Our Lord, who chose him to be one of the twelve apostles. It is believed that after the Resurrection, St. Andrew labored in spreading the Gospel in Eastern Europe, and made many converts.

At the last he was crucified in Patras in the Greek manner. In 357 his remains, together with those of St. Luke, were solemnly translated to the Church of the Apostles in Constantinople. His head is venerated at St. Peter”s in Rome. In 1210 his body had been moved to the Cathedral at Amalfi in the Kingdom of Naples. His feast is important not only on account of the position it holds in the Missal (at the beginning of the Proper of the Saints) but more especially on account of the antiphons of the Divine Office and the passages from Holy Scripture read at the Mass.

(Source: Fr. Lasance, The New Roman Missal)

The day preceding a festival is styled a vigil (from the Latin word signifying a night-watch) because in primitive ages the faithful passed in prayer in the church the greater part of the evening and night preceding a festival. Nor did they break their fast until after the holy sacrifice of the Mass had been offered, and Communion given in the course of the vigil. Hence the greater vigils are still observed as fast days; and the Mass of a vigil has a special penitential character. Purple vestments are worn by the priest; the Gloria in excelsis is not said.

St. Saturninus, martyr, suffered at Rome in the last great persecution under Emperor Diocletian, 304.

(Source: Fr. Lasance, The New Roman Missal,)