ॐ तत्सदिति निर्देशो ब्रह्मणस्त्रिविधः स्मृतः | ब्राह्मणास्तेन वेदाश्च यज्ञाश्च विहिताः पुरा ||
oṁ tat sad iti nirdeśo brahmaṇas tri-vidhaḥ smṛtaḥ brāhmaṇās tena vedāś ca yajñāś ca vihitāḥ purā
Translation
Om, Tat, Sat — this is declared to be the threefold designation of Brahman. By that were ordained of old the Brahmanas, the Vedas, and the sacrifices.
Interpretation
Chapter 17 introduces the three sacred syllables that designate Brahman: Om (the primordial sound, the symbol of the Absolute), Tat ('That' — pointing to the inexpressible transcendent), and Sat (Being/Reality/Truth — that which truly exists). Together they form Om Tat Sat, the most complete verbal gesture toward the Ultimate. These three syllables are the consecration of the entire Vedic tradition: the teachers (Brahmanas), scriptures (Vedas), and rituals (yajnas) were all ordained with this threefold name of Brahman. To begin any sacred act with Om Tat Sat is to consecrate it to the Absolute.