The evening of Maundy Thursday marks the beginning of the Triduum — ‘three days’ in Latin — the most important days in the Church calendar, which conclude Easter evening.
Find out how Passover was celebrated in Jesus’s time and how important the Last Supper is to Christianity:
It is important to know that some Jews held this supper on Thursday and others on Friday, according to John MacArthur (emphases mine):
There actually were two different evenings when the Passover was celebrated. I’ll just leave it at this. The northern people in Galilee celebrated it on Thursday evening while the Judeans, the Sadducees and the people in the south celebrated it on Friday evening. This is perfect, so that Jesus could celebrate the Passover with His friends in Galilee when they celebrated it on Thursday and still die as the Passover lamb on Friday at the time when the southern Judeans were slaughtering their lambs for their Passover. So there are actually two times; on Thursday for those in the north, and on Friday for those in the south. And that’s an important reckoning because there are texts in John’s gospel, in particular, that make it necessary to understand that.
This is because of the difference in the way the two groups of Jews calculated their days:
Study Josephus. Study the Mishnah, the codification of Jewish law and other historical sources. You find that the Jews in the north and the Jewish people in the south, the Galileans say as opposed to the Judeans, had different ways of calculating their days. These chronological aspects have been a wonderful study in anybody’s…anybody who makes an effort to studying this in the New Testament is greatly enriched by it. But in the north, they calculated days from sunrise to sunrise…sunrise to sunrise. That was a day. Whereas in the south, they calculated the day from sunset to sunset. So that’s a very clear distinction. In Galilee, where Jesus and all the disciples except Judas, had grown up, they calculated days from sunrise to sunrise. So the fourteenth of Nissan was sunrise on Thursday to sunrise on Friday. That puts the Passover Thursday night. For the Jews in the south, it was sunset to sunset, so that puts it in late Friday for the southern Jews. Same day calculated two different ways. And that worked well for the Jews.
By the way, the Pharisees tended to go with the northern approach. The Sadducees who were all around Jerusalem tended to go, of course, with the southern approach. What that did was solve a couple of problems. It split the number of animals to be killed into two different periods, Thursday night and Friday night. It also reduced what were called regional clashes cause the southern people didn’t think too highly of the northern people. So it just was easier to have them separated.
The posts below are resources for John’s Gospel, which provides the fullest description of the Last Supper and Jesus’s final discourses to the Apostles:
‘One of you will betray Me’ (John 13)
These posts discuss the words of consecration, which Jesus used at the Last Supper and continue to be part of Christian liturgy today:
Peter’s three denials of Jesus took place after His arrest. Jesus foretold this when He and the Apostles were at the Mount of Olives that night:
So much happened that day. The Apostles had no idea what would happen on Friday. But Jesus knew full well, which is why He spent hours in prayer while the Twelve slept nearby.