Risen Bread

The inimitable Msgr. Pope supplies the clearest explanation, which I impart to my students:

I would add another reason for the Lord’s action of not abiding with them continuously: It was fitting for Him to do this to accustom them to the fact that they would no longer see Him as they had with their physical eyes. Once He ascended, they would see Him mystically in the Sacraments and in His Body the Church. Thus, as the Lord broke the Bread and gave it them in Emmaus, they recognized Him the Eucharist (Luke 24). Thereupon He vanished from them. It was as if to say, “You will no longer go on seeing me in the same manner. Now you will experience me mystically and in the Sacraments.”