Our Gemara on Amud Aleph refers to the mincha brought by the Sotah as “mazkeres avon—an offering that is a reminder of the sin,” based on the verse in Bamidbar (5:15).

This is an unusual phrase, and what sin are we remembering? While we might say the sin of the Sotah, Ohr Hachaim (ibid) points out that, in actuality, we don’t need any help “remembering” that—it’s why she’s there in front of the Cohen bringing the offering. A better phrase would simply be minchas avon (an offering of sin) or minchas hochacha, an accusatory offering.

The Shalah (Torah Shebiksav, Bamidbar, Nasso, Beha’alosecha, Torah Ohr, Nasso) says it’s a remembrance of the original sin of Adam. It’s not so clear from the Shalah what the precise nature of the sin is, but symbolically there are two possibilities, and his text alludes to both. There is a Midrash that the serpent seduced Chavah, which is a clear tie-in to Sotah, but this too is likely a metaphor for Chavah being seduced by sensual desires instead of maintaining a spiritual state. Shalah also alludes to man’s sin due to jealousy—presumably the jealousy of wanting to be like a god. This jealousy, wanting what does not belong to you, is the same jealousy as the adulterer.

The Shalah notes that the verse (Bamidbar 5:22), “and the woman shall say amen amen,” is also the proof text for the halachic-legal concept of gilgul shevuah. A gilgul shevuah is a rule whereby a civil plaintiff, who through his claims triggered that the defendant must make an oath, can now add on any other claims and compel him to make an oath on them as well, even though ordinarily he would not be required to. Shalah says Adam, too, literally incurred upon his descendants a gilgul shevuah in the sense that mortality and imperfection were introduced into the world. This led to the effect that if somebody would not complete the restoration of their soul when they passed away, they could be sent back as a gilgul to correct their past life. It also is literally a gilgul shevuah in the sense that we have a tradition that when a person is born, his soul is brought before God and makes an oath that he will be righteous (Niddah 30b).

Ohr Hachaim (Bamidbar ibid) also interprets the words “mazkeres avon—an offering that is a reminder of the sin” as reminiscent of the sin of Adam, but explains it differently. He also adds meaning to the ritual which involves bringing water and earth from the Temple to mix into the potion drunk during the Sotah ordeal (ibid 5:17).

The sin of Adam caused the Shekhina to depart from the world, while the giving of the Torah rectified that. Once again, that was lost with the Sin of the Golden Calf (which not coincidentally had its own Sotah-like ritual, Shemos 32:20), but still one place remained for the Shekhina—the Mishkan and Beis HaMikdash. The water represents the same lower waters that were frustrated at losing their connection to God after their separation during the creation process (see Bereishis 1:7 and Rashi Vayikra 2:12). The earth and water at the Temple site still maintain the original attachment to the Shekhina from creation, which was severely limited after the sin of Adam. This is how the Sotah ritual and sacrifice is a “mazkeres avon—an offering that is a reminder of the sin.” The ground and water that were alienated from God due to Adam’s betrayal are brought into this confrontation of another betrayal.