Torah alone (even though it is itself wisdom) does not suffice

The Alter Rebbe explains that the light of the Shechinah must garb itself in wisdom, which is oil. For (as previously explained) wisdom, or intellect, is the vessel and “garment” for the light of the Shechinah, which is — Chochmah as it is garbed in Torah. Yet, in order to draw down the light of the Shechinah so that it will shine upon the divine soul of the Jew, more than oil is necessary; one must also have a wick. Oil is transformed into light through the medium of a wick. It is the wick, which itself is burned, which keeps the fire from being extinguished. In spiritual terms the wick refers to the vivifying soul which provides the person with physical life. This wick is burned through Torah and mitzvot. Just as the physical wick burns and is annihilated by the fire, so do the garments of thought, speech and action of the vivifying soul become burned in the light of the Shechinah through the Torah and mitzvot which a Jew studies and performs. It is for this reason that the oil must also consist of “good deeds,” mitzvot, which have their source in G‑d’s wisdom; Torah alone (even though it is itself wisdom) does not suffice. For only through the action required by the mitzvot will the light of the Shechinah be drawn down into the wick — the vivifying soul. This is accomplished when the vivifying soul is burned thoroughly in the light of the Shechinah which shines on one’s head.