The Kohen Gadol performing the avoda in the Beis Hamikdash adorned by the bigdei kehuna reaches a level of sanctity that a regular person presumably can never attain. Yet Chazal tell us that a talmid chacham has precedence over a Kohen Gadol (mishna Huriyos 3:8). The Rambam elaborates upon the distinction between a Kohen Gadol and a talmid chacham as follows: Kehuna is reserved exclusively for the descendants of Aharon, while Torah belongs to the entire Jewish People. Through Torah study anyone can be elevated spiritually and even surpass the level of the Kohen Gadol. (see Rambam Hilchos Shemitah v'Yovel 13:13).
There is one halacha concerning the Kohen Gadol that, in its broadest sense, applies to all of us and whose observance is fundamental to living a life of kedusha. The Kohen Gadol wore the tzitz, which was engraved with the words "Kodesh laHashem", on his head. Although the Torah seems to describe the Kohen Gadol as wearing the tzitz at all times - "tamid" - the Torah shebaal peh explains that "tamid" does not demand that he wear it constantly, but rather "tamid" dictates that when the Kohen Gadol wears the tzitz he must always be aware that it is on him (i.e. hesech hadaas is forbidden while wearing the tzitz.) Chazal derive from this that one who is wearing tefillin must focus on the tefillin and take care that his thoughts not stray to other matters that are inconsistent with the message of tefillin. While the tzitz has the name of Hashem engraved on it, the parshiyos of tefillin contain Hashem's name many times. As such, tefillin must be treated with even more care than the tzitz. Hesech hadass should be inconceivable when the name of Hashem is upon us.
We carry the name of Hashem with us whenever we study His Torah. The Ramban in his introduction to chumash elaborates upon how the entire Torah is the name of Hashem, i.e. Hashem's Torah is a description of Him that we can relate to in this world. Just as the Kohen Gadol cannot have hesech hadaas from the message of the tzitz and one cannot have hesech hadaas from tefillin, so too, talmud Torah cannot be accomplished with hesech hadaas. This requirement that talmud Torah be free of hesech hadaas has a substantive halachic impact on our approach to birchas HaTorah. The rishonim question why we recite birchas HaTorah before we learn in the morning yet do not repeat it later in the day when we return to learning, given that if we interrupt the fulfillment of another mitzvah we recite a new bracha when we return. The explanation is given that talmud Torah is different because we are never allowed to have hesech hadaas from Torah. Even when we are involved in other activities, the mitzva of talmud Torah requires of us to constantly focus on returning to our learning as soon as possible, since talmud Torah is incumbent upon us tamid.
There is a question at the end of Orach Chaim whether one should rejoice on Purim Katan, i.e. the 14th day of Adar Rishon. The Rama supports such rejoicing by quoting the pasuk that states, "tov lev mishte tamid - one with a good heart is constantly rejoicing". The Rama thereby ends the section of Orach Chaim with the word "tamid". The commentaries on the Rama note that the Rama began Orach Chaim by quoting the pasuk, "shivisi Hashem l'negdi tamid - I have placed Hashem in front of myself at all times." One who thinks of Hashem tamid is the one who is truly happy tamid. The Koehn Gadol focuses on the tzitz tamid, and tamid governs the wearing of tefillin. It is this sense of tamid, the concentration and focus on Hashem and His Torah that is our Orach Chaim, our way of life.
As we conclude the parshioys of the mishkan and bigdei kehuna and as we transition from Adar Rishon to Adar Sheni, it is time to commit ourselves to a life of tamid. May we be zoche to once again see the Kohen Gadol wearing the tzitz tamid, inspiring us to live a life of "Kodesh laHashem tamid."