But when Shabbos comes, the Ribbono shel Olam removes the darkness. He gives a Yid a יתירה נשמה and says to him, “No, there’s no work today. Now you must be preoccupied with thanking Hashem and singing and praising Him. When you eat challah, you should understand that the Ribbono shel Olam is giving you shefa. You should give thanks for this during Birchas HaMazon, and be preoccupied with focusing on your blessings.” This is the second avodah.
On Shabbos, we ascend. There’s no avodah to engage in gashmiyus. We must only sing and praise the Ribbono shel Olam... יום הבא עולם מעין מנוחה שבת.
The Aibishter wants these two avodos to come together—He wants Shabbos to illuminate so strongly, even into the days of the week. The more a Yid feels on Shabbos that he has everything, the less he will feel lack during the days of the week. But all of this is possible only with the power of Shabbos Kodesh. Without Shabbos, we don’t have the vessels to feel this—because when we’re “down here,” we will always feel lack.