After Jesus' Resurrection from the dead, He continued to appear to His disciples for a period of 40 days. After this time, with His Apostles gathered around Him on the Mount of Olives, Jesus was taken up bodily into heaven, as recorded in the Gospels. To comfort them in His physical absence, He promised to send them a Consoler and Advocate, the Holy Spirit, to be with them and to guide them into all truth until the end of the world. The Solemnity of the Ascension of Our Lord is celebrated on the 40th day after Easter Sunday, also called Ascension Thursday. It is a Holy Day of Obligation, and among the oldest and most solemn feasts on the liturgical calendar. In many dioceses the celebration of the feast is transferred to the following Sunday.