"The Torah and the Holy One, blessed is He, are altogether one," says the Zohar. Chapter twenty-three of the Tanya explains what this means in practice—and the explanation transforms every mitzvah into something cosmic.
The 248 positive commandments, the Tikkun (spiritual repair)ei Zohar says, are the "248 organs of the King." Rabbi Schneur Zalman unpacks this metaphor. The organs of a human body are garments for the soul—they obey the soul's will instantly, without hesitation, without resistance. When you decide to move your hand, the hand moves. There is no negotiation, no delay. The body is a perfect instrument of the will.
The commandments work the same way for God. They are the innermost garment of God's innermost will. When a person performs a mitzvah, the life-force that flows through that act is pure, uncontracted divine will—not the reluctant "back" of God that sustains the shells, but the "face," the direct inner desire.
This means that when a person's hand gives charity, that hand becomes a chariot for God's will—in exactly the same way that the Patriarchs' entire bodies were chariots for God. Not metaphorically. The hand, at that moment, is a divine organ. The feet walking to perform a commandment are divine organs. The mouth speaking words of Torah is a divine organ.
The Tanya extends this to thought. When a person's brain contemplates Torah, that brain becomes clothed in the divine will and wisdom simultaneously. The mind is wrapped in God, and God is wrapped in the mind. This union, the Tanya says, is the purpose of all creation. The descent of the divine light through all the worlds, the contraction, the concealment—it all happened so that a human being in a physical body could pick up a lulav, study a page of Talmud, or put a coin in a charity box, and in that moment, become one with the Infinite.
Every mitzvah is an organ of God, activated by a human being. This is why the Tanya says the commandments are not obligations imposed from outside. They are invitations to let God inhabit your body.