We have already said that the unfamiliarity of most Christians with Jewish ritual is mostly to blame for our inability to clearly see how “Jewish” and “ritually oriented” Christ’s teachings would have been to His contemporaries. The Last Supper is a prime example of this problem.
To the modern reader, left to himself to read the Gospels and interpret them in whatever way seems most obvious, the Last Supper is a scene much like we would expect to find today: a group of friends gathered together to share in a meal, with food and drink and some pre-meal prayers involved. If there is anything unusual about this scene, it is the presence of a spiritual teacher who uses the situation (itself nothing more than a normal supper) to offer some insights into the crucifixion that was coming, and to invite his followers to remember him afterward by sharing similar meals. To this end, he breaks bread and offers wine, symbolically associating these with his body and blood as a sort of ‘visual aid’ to help future participants kindle piety through visualization and participation.
The above is perhaps an oversimplification, and many Christians will be aware of the fact that this meal coincided with the Passover feast, but the degree of ritual specificity in Christ’s words and actions will remain invisible. The invisibility of the ritualistic nature of the Last Supper then leads to a denial of the Catholic doctrine regarding the Mass, since it is clear that the nature of the latter must derive from the nature of the former.