Today is Ascension Thursday, the day on which we celebrate our Lord’s bodily Ascension into heaven on the fortieth day after Easter. Pope Saint Leo the Great refers to this period as “the divinely ordained number of forty sacred days, devoted to our practical formation.” The number forty seems to be God’s way of demonstrating “completeness,” and we see it associated Moses and Elias in the Old Testament, and with our Lord in the New. “While our Lord lingered in bodily form during this prolonged period, faith in His resurrection was fortified with needed proofs.”
Our Lord seems to have appeared first of all to Mary Magdalene, who went looking for Him in the tomb. We saw our Lord appear to the Apostles on Easter Sunday night; and we saw Him return a week later, so that the doubting Apostle Thomas might put aside the doubt of future generations by actually touching the wounds of crucifixion on His body. He appeared to two of His disciples on Easter Monday on the road to Emmaus, “and they recognized Him in the breaking of the bread.” The scriptures record at least two other times when He appeared and ate with the disciples: broiled fish and a honey comb on one occasion; fish that He cooked and bread that He baked on another occasion. Saint Paul wrote to the Corinthians that one occasion there were over five hundred witnesses to the resurrected Lord.
Many of these manifestations of our Lord involved eating—perhaps our Lord thought this a good way to demonstrate that He was no ghost, and no illusion, but a flesh and blood man who had been resurrected from the dead. There also seems to be a Eucharistic element to this. In the inn at Emmaus, “He took bread and blessed and broke ... and their eyes were opened, and they recognized Him....” And, perhaps it is no accident that Ascension Thursday is an “octave of weeks” after Holy Thursday, and today’s account opens “while eating with them, He charged them not to depart from Jerusalem.”
In any event, these forty days have been a demonstration of the reality of the Resurrection. It is also a foreshadowing of our own resurrection. Pope Saint Leo goes even a little further. He says the Apostles were “reinvigorated with great joy ... for in their presence ... human nature was lifted up and exalted above the dignity of all heavenly creation ... elevated above the heights of archangels ... till it received a seat at the throne of the eternal Father. to whose nature it was united in the Word.” And “we have the hope that the body will be summoned whither the head has preceded it in glory.” 
This is the good news that our Lord wants us to share with all mankind, that they may believe and be baptized. We are the members of the Mystical Body of Christ, of which Christ is the Head. “As in Adam all die, so in Christ all will be made to live. Christ has risen from the dead, the first fruits of all who have fallen asleep. For since by a man came death, by a man also comes resurrection of the dead.”
We rejoice today that our Lord has not left us, but will send the Holy Ghost to confirm us in the Catholic Faith, “not many days hence.” We rejoice that we will one day see Him returning in the same way as He was taken up into heaven on that Thursday many years ago. We rejoice in that by keeping His commandments we will be united with Him and the Father, partakers of His Resurrection, dwellers in the very heights of heaven.
 Homily of Pope Saint Leo the Great #1 on the Ascension of our Lord (Second Nocturn of the Feast).
 Cf. John xx: 1-18.
 Cf. John xx: 19-31.
 Luke xxiv: 13-35.
 Cf. Luke xxiv: 36-47; John xxi: 1-14.
 Cf. 1 Corinthians xv: 6
 Luke xxiv: ibid.
 Epistle of the Ascension: Acts i: 1-11
 Leo the Great, ibid.
 1 Corinthians xv: 22, 20-21.