A strange ruling sits at the heart of Jewish law. If you recite the Shema prayer entirely in your mind, with complete concentration and devotion, you have not fulfilled your obligation. You must say the words again, out loud. But if you mumble the Shema with your lips while your mind wanders, you have technically fulfilled the commandment. How can going through the motions count for more than sincere, silent devotion?
Rabbi Schneur Zalman of Liadi explains that this ruling reveals something profound about why the soul came into a body in the first place. The neshamah (נשמה), the divine soul, does not need the commandments for its own perfection. It is already a spark of God. The commandments exist to draw light downward and perfect the nefesh (נפש), the vital animating soul, and the physical body it inhabits.
This transformation happens through the letters of speech. When your lips form sacred words, that is the animal soul being recruited into holy service. The five organs of articulation, the lips, teeth, tongue, palate, and throat, become channels for divine light. Silent meditation, however beautiful, bypasses this entire mechanism.
Yet the Tanya does not dismiss intention entirely. The Shelah HaKadosh taught that "prayer without kavanah (כוונה), intention, is like a body without a soul." The words are the body. The intention is the soul. A body without a soul still exists as a body. But a soul without a body has no vessel to inhabit in this world.
The same light of the Ein Sof (אין סוף) hides within both body and soul. But the soul receives an incomparably richer illumination. Similarly, words spoken with intention carry an infinitely greater radiance than the same words spoken without. The body of the mitzvah works regardless. But the soul of the mitzvah is what makes it blaze.