Shaarei Yosher, sec. 2: Qedushah – part 1
In my opinion, this whole concept is included in Hashem’s mitzvah “Be holy, [for I am Holy].” The Midrash (Leviticus, Emor, ch. 24) says about this verse: “Can it [truly] be ‘Like Me?’ This is why it continues, ‘for I am Holy’ to teach that My Sanctity is above yours.” ולדעתי כל ענין זה נכלל במצות ה׳ של “קדושים תהיו”, דהנה במדרש ויקרא פרק כ״ד אמור על מקרא זה: “יכול כמוני? תלמוד לאמר ‘כי קדוש אני’, קדושתי למעלה מקדושתכם”,
Rav Shimon already wrote that our job is to bestow good on others, in imitation of the purpose of creation, and used the term qedushah to refer to the commitment of our abilities to that goal.
Here R’ Shimon adds that what we call “commitment” with respect to people is different in kind that Hashem’s commitment. Hashem is absolutely One. He has only One Goal. Purity of purpose is inherent.
For people, our natural state is to be in a swirl of motivations, “tov vara be’irbuvya — good and evil in mixture”. Perfect purity of purpose is an unreachable goal to continually strive strive for.
Thus, Hashem adds “for I am Holy” — that His Sanctity is above ours.
(See also the connection between the sin of eating the fruit of the tree of knowledge and this element of the human condition I drew in my earlier post “The origins of imperfection“.)