The text below is taken from a sermon of Pope St. Leo the Great (390-461 AD)
Dearly beloved, those days which intervened between the Lord’s Resurrection and Ascension did not pass by in uneventful leisure, but great mysteries were ratified in them and deep truths were revealed.
In those days the fear of death was removed with all its terrors, and the immortality not only of the soul but also of the flesh was established. In those days the Holy Ghost is poured upon all the Apostles through the Lord’s breathing upon them, and to the blessed Apostle Peter, set above the rest, the keys of the kingdom are entrusted and the care of the Lord’s flock.
It was during that time that the Lord joined the two disciples as a companion on the way, and, to sweep away all the clouds of our uncertainty, reproached them for the slowness of their timid and trembling hearts. Their enlightened hearts catch the flame of faith, and lukewarm as they have been, they are made to burn while the Lord unfolds the Scriptures. In the breaking of bread also their eyes are opened as they eat with him. How much more blessed is that opening of their eyes, to the glorification of their nature, than the time when our first parents’ eyes were opened to the disastrous consequences of their transgression.
Dearly beloved, through all this time which elapsed between the Lord’s Resurrection and Ascension, God’s Providence had this in view, to teach his own people and impress upon their eyes and their hearts that the Lord Jesus Christ had risen, risen as truly as he had been born and had suffered and died.
Hence the most blessed Apostles and all the disciples, who had been both bewildered at his death on the cross and backward in believing his Resurrection, were so strengthened by the clearness of the truth that when the Lord entered the heights of heaven, not only were they affected with no sadness, but were even filled with great joy.
Truly it was great and unspeakable, that cause of their joy, when in the sight of the holy multitude the Nature of mankind went up: up above the dignity of all heavenly creatures, to pass above the angels’ ranks and to rise beyond the archangels’ heights, and to have its uplifting limited by no elevation until, received to sit with the Eternal Father, it should be associated on the throne with his glory, to whose Nature it was united in the Son.