Does "על" mean “on” or “next to”?

Provided courtesy of Real Clear Daf

Thursday’s daf (62a) discussed this question as it pertains to how the Shavuos lambs and loaves are waved. The Gemara brings several Tannaim who grapple with the contradictory implications in the passuk regarding which part goes on top: initially the passuk implies that the lambs go on top but the verse later implies the opposite. In the opinion of Rebbi, the lambs and loaves are placed next to each other. But, the Gemara objects, the passuk says that each item goes, "על," literally, on, the other?

The Gemara explains that Rebbi’s approach here is based on an opinion that he expressed regarding the placement of the spoons of frankincense with the lechem haponim. Even though the Torah says to put the frankincense "על" the stacks of lechem haponim, Rebbi says that it is placed on the Shulchan next to the stacks, for the word "על" here is interpreted as “next to.” Rebbi establishes the validity of this interpretation from the word "על" which is stated by the curtain that separated the Kodesh Kodoshim, where the Aron was located, from the rest of the Mishkan. The Torah says to put the curtain "על" the Aron. Since we know that the curtain did not cover the Aron we have to say that "על" there means “next to.” We likewise interpret "על" by the lechem haponim and the Shavuos lambs to mean “next to.”

It’s not immediately clear how Rebbi makes the leap from the apparent meaning of "על" by the curtain to the word "על" by the lechem haponim and the Shavuos lambs: Surely Rebbi agrees that the literal meaning of this word is “on.” So while we are indeed forced to work with a different interpretation by the curtain, why does it follow that we should assume the secondary meaning in these other contexts?

Now regarding the Shavuos lambs we can answer that what forces Rebbi’s secondary interpretation is the fact that according to the conventional interpretation the passuk would be contradicting itself (as explained above: the lambs cannot be both on top and on bottom). But our daf does not provide any basis for assuming the secondary interpretation by the lechem haponim. Tosfos in Sota (37a, heading   "מאי") sheds light on the matter. Tosfos there explains that Rebbi argues that it makes more sense to put the frankincense next to as opposed to on top of the lechem haponim, for putting the frankincense on top of the bread runs the risk of causing the bread to break. Furthermore, (as we see on our daf from the way Rebbi responds to Chaninan ben Chachinai) Rebbi feel that placing the items of an offering one on top of the other is not a respectable way to present the offering.

The upshot of this is that everyone agrees to the literal definition of "על" which is “on.” Rebbi just has specific reason to depart from that literal interpretation in each context.