Two further roots to the meal are worth mentioning: temple ritual and the order of Melchizedek.
Once the people of Israel had got established in the Promised Land and the Ark of the Covenant was in Solomon’s temple various processes of worship were developed, through the temple. One central ritual was the ritual of atonement, when the sins of the community are wiped clean. The people gather for the ritual and there is a process by which the high priest slaughters a bull as atonement for his sacrifice so he becomes ritually pure, he goes into the Holy of Holies, he puts on the robe of God, the mantle of God (and he is then called 'Son of God') and he comes out and there are two goats, one is the scapegoat, one is the Lord, and he slaughters the lamb representing God and he sprinkles the blood in order to cleanse creation: it is the blood of the lamb that cleanses creation. Then he lays his hands on the scapegoat and it gets driven out and so that the sins are put away and creation is renewed. You can see how the Christian liturgy draws on this language and imagery: we are washed clean by the blood of the lamb. It is a renewing of the community and the whole creation.
One other precursor worth mentioning is referred to in Psalm 110, and in Hebrews in particular, that Jesus is our high priest for ever, after the order of Melchizedek. When I first came across this it was rather mysterious, but Genesis 14 is the source. Abraham has been involved in a battle and he gives a tribute to the local king (it could mean that he was the king of what became Jerusalem, because it is that sort of area). But Melchizedek offers a sacrifice and brings bread and wine and this is the blessing, he is acting, he is described as acting, as a priest, and this is a blessing for Abraham. So one of the keys things about this is that this is a priesthood (he is described in Genesis as a priest of the Most High God) that comes before the Levitical priesthood. As Jesus wasn’t a member of the Levitical priesthood, how can he have been a high priest? The answer is that he is a High Priest of the order of Melchizedek, which pre-dates the Levitical priesthood and is more powerful, there are all sorts of references to it being an eternal priesthood and so on, but I don’t want to go into this in too much detail as I will get out of my depth very quickly! It does seem to have been an important factor coming into what was understood.
So what does Jesus say about this meal? He says: “This is the new covenant.” He is deliberately establishing something, and it is drawing on the existing language, this old covenant, this Old Testament. (The word translated as testament is simply covenant, ie an agreement, in fact there were several agreements between God and the people of Israel.) Cultural forms like Passover and the temple ways of renewing the agreement, that covenant between God and the people - what Jesus is doing is saying this is the new agreement, God is acting again, God is renewing this process, there is a new agreement, you don’t have the old agreement any more, the old legal contract, there is a new one and this is what it is: it is the sharing of the bread and the wine.