Sotah, Chapter Two, Mishnah One
As part of the Sotah ritual, Numbers 5:15 states, And he shall bring as an offering for her one-tenth of an ephah of barley flour. No oil shall be poured upon it and no frankincense shall be laid on it, for it is a meal-offering of jealousy, a meal-offering of remembrance which recalls transgression.
From this passage we can already see that this meal-offering differs from other meal-offerings and that it is not a fancy offering, but rather base. Most of our mishnah is based on this passage, but the sages add a few flourishes of their own to the baseness of this meal-offering.
1) [The husband] brings her meal-offering in a basket of palm-twigs and places it upon her hands in order to weary her.
a) With all other meal-offerings, their beginning and their end are in ministering vessels; but with this, its beginning is in a basket of palm-twigs and its end in a ministering vessel.
2) All other meal-offerings require oil and frankincense, but this requires neither oil nor frankincense.
3) All other meal-offerings come from wheat, but this comes from barley.
4) The meal-offering of the Omer, although it comes from barley, was in the form of sifted flour; but this comes from unsifted flour.
5) Rabban Gamaliel says: just as her actions were the actions of an animal, so her offering [consisted of] animal’s fodder.
Section one: Numbers 5:18 states that the husband places the meal offering on his wifes hands. The mishnah reads this as an attempt to tire her out, and thereby convince her to admit her guilt and avoid the ceremony. Again, we see that the rabbis are trying to avoid at all costs the enactment of the ceremony, for this will cause Gods name to be rubbed out.
The mishnah adds to the humiliation, or at least lack of adornment of the ceremony, by stating that unlike all other meal-offerings, which are brought and then brought back in ministering vessels of gold and silver, this one is initially put into a simple reed basket.
Section two: This rule is stated explicitly in the verse from Numbers.
Section three: Barley was considered a much coarser grain than wheat. The fact that the Torah demands that the Sotahs meal-offering be brought from barley is again evidence of the fact that it is almost like animal food, as Rabban Gamaliel states below.
Section four: The mishnah notes that there is one other meal-offering that was also brought from barley. What distinguishes the Omer offering from that of the Sotah is the fact that the former is sifted and the latter is not.
Section five: The final note of our mishnah is clearly where the whole passage was headed. The meal-offering of the Sotah is symbolic of her (albeit) alleged crime of adultery. Uncontrolled sexuality is not proper behavior for human beings; it is behavior fit for an animal. To symbolize this, the Torah and Rabbis made the Sotahs meal-offering close to animal food.