1) WHY MAY A KOHEN GADOL NOT PERFORM AVODAH WITH THE "BEGADIM" OF A KOHEN HEDYOT?
QUESTION: The Gemara states that any Avodah done by a Kohen Gadol who is wearing the Begadim of a Kohen Hedyot is Pasul. This is derived from the verse, "And the sons of Aharon ha'Kohen will place" (Vayikra 1:7). The word "ha'Kohen" is extra, indicating that there is a certain aspect of Kehunah that applies specifically to Aharon. The Gemara understands that this teaches that the Kohen Gadol must perform Avodah only in his special Begadim, and not in the Begadim of a Kohen Hedyot.
TOSFOS (DH Hagah) asks that this seems to contradict the Gemara in Yoma (12b). The Gemara there quotes Rebbi Yosi who says that a Kohen Gadol who served merely as a temporary replacement for the permanent Kohen Gadol may no longer serve in the Beis ha'Mikdash after the permanent Kohen Gadol returns. The reason why the temporary Kohen Gadol may no longer serve as a Kohen Gadol is that it would cause enmity between the two Kohanim Gedolim. He also may not serve as an ordinary Kohen Hedyot because of the rule of "Ma'alin b'Kodesh v'Lo Moridin" -- once a person (or object) achieves a higher status of holiness, his status may not be lowered but only raised to a higher level.
If the temporary Kohen Gadol is really a Kohen Gadol, but he cannot serve in order to prevent enmity between the two Kohanim Gedolim, then there is a more basic reason than "Ma'alin b'Kodesh" for why he cannot serve as a Kohen Hedyot. The Gemara explicitly states that he may not perform Avodah, because his Avodah would be Pasul since he is not wearing the Begadim of a Kohen Gadol. Why does Rebbi Yosi not give this reason? Does he disagree with the Gemara here?
(a) TOSFOS answers that Rebbi Yosi understands that the temporary Kohen Gadol may be removed from his position as Kohen Gadol by those who are empowered to appoint a person as Kohen Gadol -- the king of Yisrael and the other Kohanim. [The RAMBAM in Hilchos Klei ha'Mikdash (4:15) writes that Beis Din appoints the Kohen Gadol. This also seems to be the opinion of Tosfos in Megilah 9b, DH v'Lo l'Kohen Hedyot.) Once the king declares that this temporary Kohen Gadol is no longer the Kohen Gadol, the Kohen becomes a Kohen Hedyot and is able to serve in the Beis ha'Mikdash with the Bigdei Kehunah of the Kohen Hedyot, were it not for the law of "Ma'alin b'Kodesh."
(b) The ITUREI MEGILAH on Megilah (9b, note 4) explains that according to the Rambam, Rebbi Yosi means that the temporary Kohen Gadol is appointed only to be a temporary Kohen Gadol, and he is no longer a Kohen Gadol once the original Kohen Gadol returns. What does this mean? The Gemara says that the reason why the Kohen may not continue to serve as Kohen Gadol is due to enmity, which implies that he does have the status of a Kohen Gadol after the original Kohen Gadol returns. The Iturei Megilah explains that the intention of the Gemara is the opposite. The Gemara means that although this Kohen should become a Kohen Hedyot, he may not serve as a Kohen Hedyot because of "Ma'alin b'Kodesh." Why, though, does he not serve as a second Kohen Gadol? The Gemara answers this would cause enmity between the two Kohanim Gedolim.
(c) The RITVA in Yoma (12b) answers that when the Gemara explains that the temporary Kohen Gadol cannot serve as a Kohen Hedyot because of "Ma'alin b'Kodesh," it actually means because of "Mechusar Begadim." Since this Kohen no longer may serve as a Kohen Hedyot because of "Ma'alin b'Kodesh," he cannot perform any Avodah because of "Mechusar Begadim." The Ritva apparently does not agree with Tosfos' opinion that a Kohen can be demoted from his status as Kohen Gadol by a mere verbal statement.
Indeed, RAV Y. S. ELYASHIV shlit'a (in HE'OROS B'MASECHES YOMA) asks many questions on the opinion of Tosfos that a Kohen Gadol can be demoted to a Kohen Hedyot. Among his questions he asks that the Gemara in Horayos (12b) discusses whether or not a Kohen Gadol who has Tzara'as may marry an Almanah. If a Kohen Gadol can be demoted, then what is the Gemara's question? Let him be demoted so that he may marry an Almanah! He concludes that the words of Tosfos need further analysis. (Y. MONTROSE)
2) HALACHAH: "KESUS LAILAH"
OPINIONS: The Gemara quotes a Beraisa which states that the verse of "u'Re'isem Oso," "and you will see it" (Bamidbar 15:39), excludes "Kesus Lailah" from the obligation of Tzitzis. The Gemara in Menachos (43a) attributes this opinion to Rebbi Shimon. The Rishonim (see, for example, the RIF in Menachos) rule that the Halachah in this matter follows the view of Rebbi Shimon.
What exactly is "Kesus Lailah"?
(a) The RAMBAM (Hilchos Tzitzis 3:7) writes that one should not put woolen Tzitzis on a linen garment, lest one come to wear that garment at night, when there is no Mitzvah of Tzitzis. Apparently, the Rambam means that although the Mitzvas Aseh of Tzitzis overrides the Mitzvas Lo Sa'aseh of Kil'ayim and, therefore, one should be able to wear Tzitzis that are Sha'atnez, one should not make such Tzitzis lest he come to wear them at night when there is no Mitzvah to override the Lo Sa'aseh of Kil'ayim. This statement, however, needs further explanation. If the Rambam maintains that "Kesus Lailah" means clothing designated specifically as nightwear, then why does the Rambam not agree that one may put woolen Tzitzis on a linen garment if the garment is intended to be worn during the day? When one wears such a garment at night, he also fulfills the Mitzvah! Apparently, the Rambam maintains that any garment worn at night is exempt from Tzitzis because of the Halachah of "Kesus Lailah."
(b) The ROSH in Menachos (Hilchos Tzitzis #1) quotes RABEINU TAM who says that "Kesus Lailah" refers to any garment which is designated to be worn at night. However, one fulfills the Mitzvah of Tzitzis at night by wearing regular clothes that one normally wears during the day (even if they are meant to be worn both during the day and at night). Rabeinu Tam disagrees with the Rambam's ruling regarding Kil'ayim, stating that one indeed would fulfill the Mitzvah of Tzitzis at night by wearing a garment that contains Kil'ayim, and thus he would not transgress the prohibition of Kil'ayim.
This argument has a practical application. Does one recite a blessing on a Talis (or Talis Katan) when he puts it on at night? According to Rabeinu Tam, one would recite a blessing in such a case. According to the Rambam, one would not recite a blessing when he puts on Tzitzis at night, since this is "not the time of the Mitzvah," as the Rambam explicitly rules (Hilchos Tzitzis 3:8). The SEMAK (#31) writes that the RITZBA used to put on his Talis on Yom Kippur night with a blessing, since he followed the opinion of Rabeinu Tam.
HALACHAH: The SHULCHAN ARUCH (OC 18:1) quotes both the opinion of the Rambam and the opinion of the Rosh (Rabeinu Tam). The REMA writes that "Safek Berachos l'Hakel" -- in doubts regarding blessings the law is lenient, and therefore one would not recite a blessing for putting on Tzitzis at night. Similarly, one would not recite a blessing even during the day for putting on nightwear that has Tzitzis on it, since Rabeinu Tam rules that this type of clothing is exempt from the Mitzvah of Tzitzis. Accordingly, the Rema writes, on the eve of Yom Kippur one should put on his Talis before nightfall in order to be able to recite a blessing on his Talis according to all opinions.
The MISHNAH BERURAH (OC 18:2) points out that although the Rema focuses on the law of reciting the blessing for Tzitzis, one also must be stringent and not wear sleepwear without Tzitzis during the day (since, according to the Rambam, one is obligated to place Tzitzis on such a garment), and not wear at night clothing normally worn during the day without Tzitzis (since, according to Rabeinu Tam, one is obligated to place Tzitzis on such a garment). (Y. MONTROSE)