then with regard to a non-priest, who may not partake of the meat of offerings of the most sacred order, is it not right that if he performed sacrificial rites he has desecrated the service?

The Gemara rejects the inference: One cannot draw an a fortiori inference from a blemished priest, as what is notable about the case of a blemished priest? It is notable in that the Torah rendered an animal that is sacrificed like the priest who sacrifices it, i.e., both blemished animals and blemished priests are disqualified. Since there is an added element of stringency with regard to the case of a blemished priest, one cannot draw an a fortiori inference from it.

The Gemara suggests: The case of an impure priest will prove that this is no reason to reject the a fortiori inference. While an animal and the priest are not equated with regard to ritual impurity, as an animal cannot become impure while alive but a priest can, an impure priest desecrates the service. The Gemara rejects this as well: What is notable about the case of an impure priest? It is notable in that an impure priest imparts impurity to others.

The Gemara responds: A blemished priest will prove that this is no reason to reject the inference, as he cannot impart his blemish to others. And the inference has reverted to its starting point. Therefore, one may derive the halakha of a non-priest from the combination of the case of a blemished priest and that of an impure priest: The aspect of this case is not like the aspect of that case, and the aspect of that case is not like the aspect of this case. Their common element is that they are prohibited from performing sacrificial rites and if they performed these rites they have desecrated the service. Therefore, I will also include a non-priest, who is prohibited from performing sacrificial rites, and conclude that if he performed sacrificial rites he has desecrated the service.

The Gemara asks: From where do we derive that a non-priest is prohibited from performing sacrificial rites? If it is derived from the verse: “Speak to Aaron and to his sons, that they separate themselves from the sacred items of the children of Israel, and that they not profane My holy name” (Leviticus 22:2), then the a fortiori inference is unnecessary, since profanation itself is writ-ten in the verse. Rather, it must be that it is derived from the verse: “Keep the charge of the Tent of Meeting, whatever the service of the Tent may be; but a common man shall not draw close to you” (Numbers 18:4).

The Gemara asks: Still, the a fortiori inference drawn from the cases of a blemished priest and an impure priest can be refuted: What is notable about their common element? It is notable in that a blemished priest and an impure priest were not permitted to perform sacrificial rites on a private altar during times when there was no Temple or permanent Tabernacle. Since it was permitted for non-priests to perform rites on private altars, perhaps non-priests do not desecrate the sacrificial rites performed in the Temple.

The Gemara responds: Do not say that the case of an impure priest will prove the a fortiori inference with the case of a blemished priest; rather, say that the case of an acute mourner will prove it, as it is prohibited for him to perform the service and, if he were to perform it, he would desecrate it. This, too, is rejected: What is notable about the case of an acute mourner? It is notable in that he is prohibited from partaking of second tithe, whereas a non-priest may partake of second tithe. The Gemara responds: A blemished priest will prove the inference, as he may partake of second tithe.

And the inference has reverted to its starting point. The aspect of this case is not like the aspect of that case. Their common element is that they are prohibited from performing sacrificial rites ab initio, and they desecrate the service if they do so. Therefore, with regard to a non-priest, who is prohibited from performing sacrificial rites, if he performed sacrificial rites he has desecrated the service.

The Gemara asks: Here, too, let one refute the inference: What is notable about their common element? It is notable in that both an acute mourner and a blemished priest were not permitted to perform sacrificial rites on a private altar, unlike a non-priest. Rav Samma, son of Rava, objects to this: And who shall say to us that an acute mourner was prohibited from performing rites on a private altar? Perhaps it was permitted for him to perform the rites on a private altar.

Rav Mesharshiyya says: The halakha that a non-priest desecrates the service is derived by an a fortiori inference from the case of a priest who performed sacrificial rites while sitting: Just as with regard to a priest who was sitting, who may partake of the meat of offerings, if he performed sacrificial rites he has desecrated the service, then with regard to a non-priest, who may not partake of the meat of offerings of the most sacred order, is it not right that if he performed sacrificial rites he has desecrated the service?

The Gemara rejects this: What is notable about the case of a sitting priest? It is notable in that one who sits is disqualified from bearing witness, as witnesses must stand when testifying. Since there is an added aspect of stringency with regard to the case of a sitting priest, one cannot derive the halakha with regard to a non-priest from it. The Gemara responds: Learn instead from the halakha of a sitting Torah scholar, as the court may allow a Torah scholar to sit while testifying.

The Gemara challenges: Still, one cannot derive the halakha from this, as what is notable about the category of a sitting priest? It is notable in that generally speaking, one who sits is disqualified from bearing witness, even though there are exceptions. The Gemara responds: The category of a sitting priest cannot refute the derivation. One can refute a derivation only from concrete cases, not general concepts. And even if you say it can refute the derivation, the halakha with regard to a non-priest can be derived from the case of a sitting priest and from one of those other cases, i.e., a blemished priest, an impure priest, or an acute mourner, all of whom may testify.

The Gemara asks: And from where do we derive that one who is sitting is fit to perform sacrificial rites on a private altar? If he is not, one can refute the common element in the same manner as above. The Gemara responds: The verse states: “The Lord separated the tribe of Levi to bear the Ark of the Covenant of the Lord, to stand before the Lord to minister to Him” (Deuteronomy 10:8). The verse indicates that the sacrificial rites must be performed while standing only before the Lord, i.e., in the Temple, where the Divine Presence resides, and not before a private altar, which is a mere place of worship.

§ The mishna teaches that rites performed by an acute mourner are disqualified. The Gemara asks: From where do we derive this? As it is written with regard to a High Priest who is an acute mourner: “And he shall not leave the Sanctuary, and he will not profane the Sanctuary of his God” (Leviticus 21:12). One can infer: But any other ordinary priest who did not leave the Sanctuary while he was an acute mourner and continued to perform the service has desecrated the rites he performed.

Rabbi Elazar says: One can derive it from here instead: When Moses asked Aaron why the sin offering that was sacrificed on the day that Nadav and Avihu died was burned and not eaten, he suspected that Aaron’s other sons, Eleazar and Itamar, had sacrificed the sin offering while acute mourners, which disqualified it and forced them to burn it. Aaron responded to Moses: “This day have they offered their sin offering?” (Leviticus 10:19). Rather, I offered it. As High Priest, I do not desecrate the Temple service even when I am an acute mourner; I burned it only because, as acute mourners, my sons and I are prohibited from partaking of the meat. Rabbi Elazar continues: By inference, one can derive that if they had offered the sin offering they would have disqualified it, and it would have been proper that it was burned.

The Gemara asks: And what is the reason that Rabbi Elazar does not say that this halakha is derived from the verse: “And he shall not leave the Sanctuary”? The Gemara responds: He could have said to you: Is it written: But any other ordinary priest that did not leave the Sanctuary has desecrated the rites he performed? It is only an inference, and so it is not conclusive.

The Gemara asks: And the other Sage, who derives it from the verse: “And he shall not leave the Sanctuary,” what is the reason that he did not say to derive it from the verse: “This day have they offered their sin offering?” The Gemara responds: He holds that the sin offering was burned because it became ritually impure, not because Aaron and his sons were acute mourners.

A tanna of the school of Rabbi Yishmael taught: The halakha is derived by an a fortiori inference from the case of a blemished priest: And just as