We have heard in the first reading the beginning of the Acts of the Apostles and in the third reading the conclusion of the gospel of Luke. These two books of the New Testament were written by the same author, the evangelist Luke; they constitute, as it were, only one work: the gospel narrates the earthly life of Jesus; the Acts of the Apostles deals with the mission of the Church, that is a different way for Jesus to be present in the world. The hinge that connects the two books is exactly the ascension of Jesus: this event closes the gospel and opens the Acts.
Even the instructions that Jesus gives to his disciples before leaving them are similar: he first renews the promise of the Holy Spirit, and then he invites them to be his witnesses in the world. The two things are closely related: the disciples will be witnesses of Jesus precisely because they will receive the Holy Spirit; it is the Holy Spirit that will enable them to bear witness to Christ.
But there is a discrepancy between the gospel and the Acts. At the end of the gospel it seems that the ascension happens on the night of the very day of the resurrection; instead, in the Acts this event takes place forty days after the resurrection. We can explain this discrepancy saying with the Catechism that the ascension is, at the same time, a historical and transcendent event (n. 660). In the gospel Luke emphasizes the transcendent aspect of the ascension, that is to say, he closely associates the ascension with the resurrection: they are two faces of the same mystery, namely, of the paschal mystery. The glorification of Jesus had already happened with his resurrection.
Indeed, the second reading shows us that this glorification had already taken place in Jesus’ death. Jesus entered the sanctuary, that is, heaven when he shed his blood on the cross. At that moment he did what the high priest symbolically used to do once a year entering the Holy of Holies in the temple to take away the sins of the people. Passion, death, resurrection, ascension and outpouring of the Holy Spirit belong to the one paschal mystery.
In the Acts of the Apostles, instead, Luke historicizes the ascension, that is to say, he tells us what really happened from the historical point of view: after his resurrection, Jesus appeared to his disciples for forty days. It was necessary to do this, so that they might become convinced of the resurrection. They had not only to believe that Jesus was alive, but also that from then on he would be with them in a different way. Actually, when Jesus left them, the disciples were not sad. The gospel says that they “returned to Jerusalem with great joy, and they were continually in the temple praising God.” By then, they knew that Jesus was with them, even if they did not see him any more. There is no need of seeing Jesus, when you know that he is with you.
Just as Jesus had not left the Father when he came down onto the earth, so now, going back to heaven, he does not leave his disciples alone in the world. By now he constitutes only one reality with them, the Church, which is his body: he is the head of the body and the disciples are its members. The head is now in heaven, seated at the right hand of the Father; the body is still on the earth, to continue his mission. The head has gone before into heaven, to prepare a place for his disciples; these will follow him. In the meantime, he uses them to continue his work in the world; through them he makes himself present among men. Staying at the right hand of the Father, as the high priest, he intercedes for them, he supports them in their journey, waiting for them to reach him.
If Jesus is with us on earth, we have to be with him in heaven. If he, seated at the right hand of the Father, is waiting for us, we, still pilgrims on earth, should look forward to rejoining him in the heavenly homeland.