Principal Upanishad · Krishna Yajurveda
Taittiriya Upanishad 2.1
Truth, knowledge, infinity — Brahman
सत्यं ज्ञानमनन्तं ब्रह्म। यो वेद निहितं गुहायां परमे व्योमन्। सोऽश्नुते सर्वान्कामान्सह।
Brahman is truth, knowledge, and infinity. One who knows Brahman hidden in the cave of the heart, attains all desires simultaneously.
What this verse points to
Satyam jnanam anantam brahma. Three words used as a definition, though the tradition reads them as removing limits rather than fixing a description — not true as opposed to false, but that which does not depend on anything to be so.
The verse then places it "in the cave of the heart," repeating the pattern the Upanishads use constantly: the largest possible claim, immediately followed by the most intimate possible location.
Sit with it
Hold the three words one at a time for a few breaths each, without trying to work out what they mean.
About the Taittiriya Upanishad
Best known for its analysis of the five sheaths (koshas) that layer over the Self — food, breath, mind, understanding, and bliss — and for closing with the disciple's repeated exclamation of having found that bliss.
References to this text are given as chapter.section — here, 2.1.