Tanya for the 18th of Menachem Av, י׳׳ח מנחם אב

The radiance emanating from the “form” of the letters—a radiance that emanates from G-d’s attributes, wisdom, and will—is merely found בְּתוֹכוֹ, within the internality of the Divine utterance that creates and vitalizes this world; it is not manifest. That which serves as the source of the creation and vitality of this world is the externality or “body” of the letters, the “breath” of Divine speech.