1 The Lord's Supper, as set forth in John, must, with His assistance, be unfolded in a becoming number of Lectures, and explained with all the ability He is pleased to grant us. “Now, before the feast of the passover, when Jesus knew that His hour had come that He should depart out of this world unto the Father, having loved His own who were in the world, He loved them unto the end.” Pascha (passover) is not, as some think, a Greek noun, but a Hebrew: and yet there occurs in this noun a very suitable kind of accordance in the two languages.
For inasmuch as the Greek word paschein means to suffer, therefore pascha has been supposed to mean suffering, as if the noun derived its name from His passion: but in its own language, that is, in Hebrew, pascha means passover; because the pascha was then celebrated for the first time by God's people, when, in their flight from Egypt, they passed over the Red Sea. And now that prophetic emblem is fulfilled in truth, when Christ is led as a sheep to the slaughter, that by His blood sprinkled on our doorposts, that is, by the sign of His cross marked on our foreheads, we may be delivered from the perdition awaiting this world, as Israel from the bondage and destruction of the Egyptians; and a most salutary transit we make when we pass over from the devil to Christ, and from this unstable world to His well-established kingdom.
And therefore surely do we pass over to the ever-abiding God, that we may not pass away with this passing world. The apostle, in extolling God for such grace bestowed upon us, says: “Who has delivered us from the power of darkness, and has translated us into the kingdom of the Son of His love.” This name, then, of pascha, which, as I have said, is in Latin called transitus (pass over), is interpreted, as it were, for us by the blessed evangelist, when he says, “Before the feast of pascha, when Jesus knew that His hour had come that He should pass out of this world to the Father.”
Here you see we have both pascha and pass-over. Whence, and whither does He pass? Namely, “out of this world to the Father.” The hope was thus given to the members in their Head, that they doubtless would yet follow Him who was “passing” before. And what, then, of unbelievers, who stand altogether apart from this Head and His members? Do not they also pass away, seeing that they abide not here always? They also do plainly pass away: but it is one thing to pass from the world, and another to pass away with it; one thing to pass to the Father, another to pass to the enemy. For the Egyptians also passed over [the sea]; but they did not pass through the sea to the kingdom, but in the sea to destruction.
Source: Tractates on the Gospel of John (New Advent)