Gemara

Rav visited Rav Shila's locale. There was no one else to translate and broadcast for Rav Shila, so Rav did so. When Rav Shila realized who his translator was, he asked Rav (who was a greater Chacham) to stop.

Version #1 (Rav): One who accepts a job should complete his work even if it is lowly.

Version #2 (Rav): We ascend in Kedushah, we do not descend (it would belittle the Drashah if a lower Chacham finishes translating)!

Berachos 28a: R. Gamliel was deposed from being Nasi to defend the honor of R. Yehoshua. After R. Yehoshua was appeased, they wanted to reinstate R. Gamliel. However, they could not depose R. Elazar ben Azaryah (who had been appointed Nasi), for we ascend in Kedushah, we do not descend!

They concluded that R. Gamliel will expound three weeks, and R. Elazar on the fourth.

Megilah 25b - Mishnah: City dwellers that sold the street (it has Kedushah because people pray there on Ta'anesim) may buy a Beis ha'Keneses with the money. If they sold a Beis ha'Keneses, they may buy an Aron. If they sold an Aron, they may buy coverings (for a Sefer Torah). If they sold coverings they may buy Seforim; if they sold Seforim, they may buy a Sefer Torah.

It is forbidden to descend (if they sold a Sefer Torah, they may not buy Seforim, etc.).

The same applies to money left over.

27a - Question: May we sell an old Sefer Torah to buy a new one?

Since we do not raise the Kedushah, it is forbidden;

Or perhaps, since there is no higher Kedushah, it is permitted!

Answer: The Mishnah forbids to sell a Sefer Torah to buy Seforim. This implies that we may sell it to buy a Sefer Torah!

Rejection: That is b'Di'eved. The question is whether or not we may sell l'Chatchilah.

(The question is left unresolved.)

Zevachim 89a - Mishnah: Whatever is more Kodesh comes first.

Rishonim

Rif and Rosh (Megilah 7a and 4:1) bring the Mishnah.

Rambam (Hilchos Tefilah 11:14): One may convert a Beis ha'Keneses to be a Beis Medrash, but not vice-versa, because a Beis Medrash is more Kodesh. If city dwellers sold a Beis ha'Keneses they may buy an Aron; if they sold an Aron, they may buy coverings for a Sefer Torah; if they sold coverings they may buy Chumashim; if they sold Chumashim, they may buy a Sefer Torah. If they sold a Sefer Torah they buy another Sefer Torah, for there is no higher Kedushah. The same applies to money left over.

Kesef Mishneh: The Rambam holds that one may not sell to buy something of the same Kedushah, only for a higher Kedushah. There is no higher Kedushah than a Sefer Torah. Therefore, b'Di'eved, if one was sold, another must be bought.

Rambam (Hilchos Sanhedrin 17:9): If the Rosh Yeshiva (i.e. the Nasi - see Sanhedrin 1:3) sinned, we lash him in front of three, and he does not return to his position. He does not even return to be a regular member of the Sanhedrin, because Ma'alin b'Kodesh v'Lo Moridin.

Poskim

Shulchan Aruch (OC 25:1): After putting on a Talis with Tzitzis he puts on Tefilin, for we ascend in Kedushah. If one puts his Talis and Tefilin in the same bag, he should not put the Tefilin on top, lest (next time) he encounter the Tefilin first and he will have to put them on first, to avoid passing over the Mitzvah.

Question: A Mishnah (Zevachim 89a) teaches that whatever is more Kodesh comes first!

Answer #1 (Dagul me'Revavah): The Beis Yosef (DH v'Achar, citing Nimukei Yosef) says that Tzitzis has precedence because it is equated to all the Mitzvos. Also, Tzitzis is more Tadir than Tefilin (it applies even on Shabbos and Yom Tov).

Rebuttal (Sha'agas Aryeh 28): Most Poskim hold that (mid'Oraisa) Tefilin applies at night, but Tzitzis does not, so Tefilin is Tadir. And even according to the opinion that Tzitzis is Tadir, since Tefilin is a matter of Kedushah, one may fulfill first whichever he wants.

Answer #2 (Chasam Sofer): The Shulchan Aruch teaches that one should remove the Talis from the bag first, in order that he will put it on first and fulfill Ma'alin b'Kodesh. Indeed, if both are out of the bag, what is more Kodesh comes first (unless the other is Tadir, in which case one may fulfill first whichever he wants). The Nimukei Yosef teaches that according to the opinion that Tzitzis is more Tadir, since Tzitzis is equated to all the Mitzvos, in this sense it is more Kodesh, therefore it comes first.

Bi'ur Halachah (DH she'Ma'alin): The person must ascend in Kedushah. First he covers himself with a Mitzvah, then through Tefilin he ties himself to Kedushah.

Shulchan Aruch (34:1): One should not put Rashi Tefilin and R. Tam Tefilin in the same bag, for one of them is not Kodesh. Rather, he should make a bag for each and label them so he will not put one Tefilin in the other bag.

Mishnah Berurah (34:20): If one found Tefilin straps, he may use them for Rashi Tefilin. Most straps are for Rashi Tefilin. Also, we hold that Rashi Tefilin are primary, so even if they were used for R. Tam Tefilin, Ma'alin b'Kodesh.

Shulchan Aruch (42:1): One may convert a strap used for Tefilin Shel Yad to be for Tefilin Shel Rosh, but not vice-versa. This is because Shel Rosh contains two of the letters of 'Shakai', so it is more Kodesh.

Mishnah Berurah (3): One should not reverse the strap so that the part that formed the Kesher will no longer do so. If he has no other way to fulfill the Mitzvah, it is permitted.

Shulchan Aruch (137:2): When three people read from the Torah, (at the least) two read three verses and one reads four. Whichever reads four is praiseworthy.

Magen Avraham (2): If the first reads four this is praiseworthy, for we find that the most important comes first. If the middle reads four this is praiseworthy, just like the middle Ner (ha'Ma'aravi) of the Menorah was most important. If the last reads four this is praiseworthy, for Ma'alin b'Kodesh. We do not learn from Ner Chanukah to say that Ma'alin b'Kodesh is preferable, for Ma'alin b'Kodesh does not apply so much when different people do the Mitzvos.

Shulchan Aruch (153:2): If one sold coverings (for Seforim), the money may be used to buy Seforim, i.e. individual Chumashim, or Nevi'im or Kesuvim. Money of Seforim may be used to buy a Sefer Torah. Money of a greater Kedushah may not be used to buy a lower Kedushah.

Shulchan Aruch (153:4): Some forbid to buy something else of the same Kedushah.

Beis Yosef (DH v'Chosav Od): The Gemara did not resolve whether or not one may buy something else of the same Kedushah. The Ran infers that it is forbidden, because the question was asked only regarding a Sefer Torah, in which case there is no greater Kedushah to buy, but when there is it is forbidden to buy the same. i

Shulchan Aruch (ibid.): Some permit to buy the same Kedushah.

Source (Beis Yosef, ibid.): Mahari Avuhav infers from the Tur that the Isur is only to decrease the Kedushah; he also cites this in the name of R. Yonah.

Source (Gra DH v'Yesh): The Gemara inferred that one may not sell a Sefer Torah to buy Seforim, but we may sell to buy a Sefer Torah. The Gemara rejected this by saying that this is only b'Di'eved. It did not say that the inference from the Seifa forbids to buy the same Kedushah.

Question (Taz 1): The question was not settled regarding a Sefer Torah, so we must be stringent! The Tur and Shulchan Aruch (YD 270:1) forbid selling an old Sefer Torah to buy a new one; why does the Shulchan Aruch bring two opinions here? All the more so we must be stringent in other cases, when it is possible to buy a greater Kedushah!

Answer (Magen Avraham 4): L'Chatchilah it is forbidden to sell. The Shulchan Aruch brings two opinions about whether or not b'Di'eved the money may be used for the same Kedushah. The Rambam permits to sell a Beis ha'Keneses l'Chatchilah, but that is different because its Kedushah can be transferred.

Mishnah Berurah (11): The Taz (1) says that many people sell Seforim and buy others. We must say that this was their intent from the beginning, even if they did not explicitly say so. This reasoning is used elsewhere, e.g. to explain why we benefit from Divrei Kedushah in a Beis ha'Keneses (Rema 154:8). Eliyahu Rabah says that they rely on the opinion (in Sa'if 10) that an individual may sell his own Sefer Torah, but one may not sell a Sefer of the Tzibur.

Kaf ha'Chayim (19): The Halachah does not follow that opinion in Sa'if 10. Rather, one may sell to buy a Sefer that is of higher Kashrus or beauty. One must deposit the money with someone else, lest he slacken to buy the new one.

Kaf ha'Chayim (125:10): Some say that when rising on one's toes when saying 'Kadosh Kadosh Kadosh', each time he rises higher because Ma'alin b'Kodesh. This is not like the Ari Zal. Rather, each time he rises the same amount.