Guarding the inner Divine spark

במדרש שנמשלו בנ"י לזית מה שמן אינו מתערב כו' צף למעלה כו'.

The Midrash says that Bnei Yisrael are compared to the olive: just as oil does not mix [with other liquids] and floats above them, so too Bnei Yisrael.

The Sefas Emes brings the Midrash that likens Bnei Yisrael to olive oil, which never blends into other liquids but always rises to the top - a sign of an essence that cannot be absorbed into anything foreign.

וע"ז נאמר ויקחו אליך שמן זית כו'.

Concerning this it says, "And they shall take to you pure olive oil…" (Shemos 27:20).

The mitzvah to bring olive oil for the Menorah alludes to this very quality of Bnei Yisrael - the unmixable inner light.

שזה המבוקש מבני ישראל לשמור חיות הפנימי.

For this is what is asked of Bnei Yisrael: to guard the inner vitality (chiyus penimi).

The avodah of a Yid is to protect the penimiyus - the inner life-force that connects him to Hashem - and not let it be dulled by the surrounding world.

חלק אלקי שיש בכל איש ישראל שלא יתערב בגשמיות.

The Divine portion (chelek Eloka) that is within every Yid, that it should not become mixed into the physical.

Every Jew carries a Divine spark, a piece of Hashem above; the task is to keep that spark from being swallowed up by gashmiyus (materiality).

ויהי' צף למעלה:

And it shall float above.

Like the oil that rises above the water, the inner Divine point in a Yid stays above the physical and is never overwhelmed by it.

Summary: Bnei Yisrael are like olive oil - the Divine spark within each Yid cannot truly mix into the physical world but always rises above it. The mitzvah of the Menorah oil teaches that our avodah is to guard this inner vitality and keep it floating above gashmiyus.