> What does iconographic evidence from Late Antiquity and the early Middle
> Ages tell us about this question?
> Patrick Nugent.
I'm not sure about the early Middle Ages, but there is a well-known
Ottonian ivory relief of a priest saying mass behind the altar and
facing the congregation, whereas all later medieval representations
have the priest on the same side of the altar as the congregation.
I've tried to trace this change in relation to the development of
altarpieces, which pretty much presuppose the priest in front of the
altar, rather than behind it. The earliest surviving ones date from
the 12th century, I believe, and they take over from antependia, or
altar frontals, which are more suited to the priest standing behind
the altar. I seem to remember that the change did not take place all
at once, and it strikes me that it began in Rome, perhaps as early as
the 11th century, and only slowly disseminated through the rest of
Europe, not becoming general until perhaps as late as the 13th
century. This change was also necessary for the placing of altars
against the eastern walls of chapels, or against choir screens,
piers, etc. It's a messy business.