Holiness is an elusive concept. The Hebrew, qadosh ("holy"), means that which is set aside from the daily, routine sphere of our lives.
Among the items found in this week's Torah reading, Parashat Shemini, is a list of animals that we are permitted to eat and those that are forbidden. We know of this concept as kashrut, that is, foods that are "kosher."*
But what is the reason given for kashrut? It is not that the permitted animals are cleaner, or healthier, or better-behaved. Rather, it is only that these are the ones that God has indicated are within the bounds of holiness. See Leviticus 11:45:
כִּי אֲנִי יְהוָה, הַמַּעֲלֶה אֶתְכֶם מֵאֶרֶץ מִצְרַיִם, לִהְיֹת לָכֶם, לֵאלֹהִים; וִהְיִיתֶם קְדֹשִׁים, כִּי קָדוֹשׁ אָנִי.
Ki ani Adonai hama-aleh etkhem me-eretz Mitzrayim lihyot lakhem lelohim; vihyitem qedoshim ki qadosh ani.
For I the Lord am He who brought you up from the land of Egypt to be your God: you shall be holy, for I am holy.
The point of kashrut, as well as all the rest of the mitzvot (commandments), is to help us to find the holy moments. It's not just about food - it also includes everything we do. And sometimes, all you need to do is focus, to look beyond the day-to-day mundanities, to find those parts of your life that are fittingly set aside.
* The Hebrew word is "kasher" (accent on the second syllable), meaning "fitting." Our English word "kosher" comes from the Yiddish/Ashkenazi pronunciation of the Hebrew word; the French, however, pronounce it like the Hebrew: cachère.