Thursday or Sunday? Some years ago, I was visiting Vatican City and was present for Ascension Thursday Vespers in St. Peter’s Basilica. The following Sunday, however, I attended Mass elsewhere in Rome and the Ascension was celebrated there! The fact is, in many places, even in the Diocese of Rome, the Ascension is now transferred to the Sunday before Pentecost. The mystery, of course, remains the same: After his resurrection, Jesus ascended into heaven and is seated at the right hand of the Father.
Our life as Christian believers has been described as being lived between "the already and the not yet." We are already taking part in the kingdom brought by Jesus, but that kingdom has not yet reached its full expression. Our readings bring out that idea forcefully today, on this Sixth Sunday of Easter, as we approach the feasts of Ascension and Pentecost.
Passover, pasch, passage, transition...the old order has passed away. We hear today of the early Christian community transitioning from a Jewish sect to a Gentile Church. The Book of Revelation describes the transition from the Church on earth in this "valley of tears" to a Church in glory, the bride of Christ. In the gospel Jesus gives a new commandment of love. The old has passed away, "Behold I make all things new."
The risen Lord Jesus is both the Lamb of God and the Good Shepherd. The Responsorial, Psalm 100, says that "we are his people, the sheep of his flock." Today is traditionally called "Good Shepherd Sunday," because the gospel is always from John 10 - the beautiful "Good Shepherd" chapter.