We find in this weeks Parsha, that Moshe sanctified the Kohanim, following Hashem's instruction to do so. The question may be raised, why must Moshe sanctify the Kohanim? Why didn't Hashem sanctify the Kohanim by Himself.
The answer rests in a basic theme of Torah philosophy. The Torah believes that on one hand Hashem sanctifies various items, but Hashem delegates us to sanctify many items. It is a סופר who sanctifies a ספר תורה when he prepares the parchment לשמה, for the sake of the מצוה. Beit Din sanctifies the calendar by declaring the month sanctified, by declaring מקודש, מקודש. Even though Hashem sanctifies the Shabbat (בראשית ב:א), we also sanctify Shabbat by reciting Kiddush (an idea which is greatly expounded upon by Rav Soloveitchik in the second volume of his (שיעורים לזכר אבא מריז"ל).
Similarly, Kohanim are sanctified by human involvement. We see that a major part of the mission of the Jew is to sanctify much of the world. Hashem has empowered us to imitate Him and declare things holy. May Hashem give us the strength and desire to fulfill this great Mission!!