“Om tat Sad” connotes, AUM is the only truth and virtue (AUM is the insignia of Brahm that comprises Prakriti and Purusha) and it is remembered three ways since eon: 1. Brahmana’s (ritualistic scriptures), 2. Vedas (the knowledge bank) and 3. Yagya’s the projects and deeds of humankind.
Om or AUM~ is the primordial process of creations and origin of cosmos, indicator of Supreme Brahm that comprises Purusha (metaphysics) and Prakriti (physics). AUM is the source of all matters and energies. AUM is Brahm. It is personified by Bhagwan Kritsna during the discourse (Shiva represents Brahm). It is remembered in three ways: In rituals (Bhaktiyog), in knowledge of Vedas (Sankhyayog) and in actions of yagya (Karmayog).
Tat ~ ‘He’ who provides for all, is the cause all actions, the source of creations and dynamism. All life bearers reflect him, the doer in them. It’s “tat” that ensures creation, progression and termination of all the worlds.
Sad~‘is ultimate truth, eternal and everlasting existences and fact of the matter in knowledge’. Sad provides purity, honesty, impartiality, virtuosity and objectivity.
“Om tat Sad” means “Only that is truth”; because of whom every existence seems to appear and who is the creator and driver of Physical and metaphysical worlds, i.e. Prakriti and Purusha. He is Brahm and His knowledge is Brahm-Gyan. Above Him is Para, the beholder of Brahm or probably the metaphysical director of Brahm, call it Parbrahma.
After learning from Gita, One would realize the depth and importance of the messages, which cannot be understood by people in their individual lives alone, all by themselves. Therefore, it must be taught in schools so that people can plan and design their life early, and ensure that everyone engages in some kind of Purusharth, dedicated to the nation and nature. Unless we teach such socio-psychological and spiritual principles to kids in school, we would not be able to discover our true potential and originality. Science and humanities has to develop together to maintain proper balance. As Indians, despite giving religion to the world, unless we teach such logic of religions in school without political interventions, we would remain slave to the rest of the world for all ideologies and solutions to our problems, unable to customize them innovatively, and continue to import technologies, products and laws. Think!