Brendan:
A careful reading of the GIRM shows that the default is “Ad Orientem”.
In para 157 At the elevation, the priest is instructed to “Turn towards the people”
And in 158, the priest is instructed to “turn towards the Altar” (stans ad altare conversus). It uses an active verb, so the Instruction expects the priest to actually move at this point.
These instructions are meaningless in a “Ad Populum” Mass, but it really shows what the norm is. Ad Orientem
i don’t agree with saying that “ad orientem” is “the default”. i don’t think we need to look for hidden clues in the GIRM.
in 299, it says “…and [in such a way] that Mass can be celebrated at it facing the people, which is desirable wherever possible.” the “whereever” is governed by the architecture of the altar. clearly, “ad orientem” is a valid option, but the GIRM voices preference for “ad populum.” that preference is emphasized by saying that altars “should be built apart from the wall” in order to eliminate places where the option is not possible. thus in any newly built place, “ad populum” becomes the preference.
also, the instructions in the GIRM are not merely descriptive. they are there to assure that certain things happen at the proper time, and to eliminate the possibility of doing otherwise. thus, since the priest could be facing in either direction, n. 157 assures that the elevation occurs facing the people for the sake of their veneration of the Lamb. likewise, in n. 158, the instruction assures that the priest consumes the Eucharist at, and over, the altar, instead of something else.
btw, n. 157 does not instruct him
to turn. the english has “facing the people” which is correct. the latin reads: “tenens [hostia], versus ad populum, dicit:…” (holding the Host, facing (directed toward) the people, he says…)
versus is an adjective, not a verb. the same goes for n.158.
stans is the present active participle “standing” and
conversus is the perfect passive participle “turned directly toward”. it says “[the priest] standing at the altar turned directly toward [it]”.
sorry, i don’t mean to be picky, but that’s the latin. if he were instructed to do some turning, it would say “vertit” and “convertit” in the same way that it says “dicit”.
the instructions are given so that both options are operable.
personally, i think all this started because of the instructions about the tabernacle following Vatican II. previously, in order to show that the Eucharist is exaulted by the Church, the tabernacle was front and center in all (or most) Churches. then came instructions like GIRM 315 that say the tabernacle shouldn’t be on the altar used during the Mass. implementation became jumbled. some put in new altars, as in n. 299. some moved the tabernacle and continued to use the high altar
ad orientem. some moved the tabernacle and faced the people. some did neither, which IMO is like saying ‘i don’t care what is preferred or better.’ anyhow, i think this is why this discussion has lingered so long. but that’s just my take on it.