Om Tat Sat are the group of three mantras in Sanskrit found in verse 17.23 of the Bhagavad Gita. It means "Om is the mantra of Brahm, Tat is the secret mantra of Parbrahm and Sat is the secret mantra of Vishnu. "Om Tat Sat" is the eternal sound-pranava. "Om Tat Sat" represents the unmanifest and absolute reality.