From all our investigation into the origin, rise, and extent of meaning of the word _Om_ in its orthography, etymology and theology, it is evident that the Indo-Aryan mind was early infused with the idea of an absolute _Om_ corresponding with the Greek _On_ and _ôn_, and _En_ and also _Aeon_ of the Gnostics, Latin _Ens_, _Unum_ and Entity, Romance _On_ and _un_, and _one_ in English, whose unity was the source of all diversity in the plurality of creation, agreeably to the text _aham bahu Syám_ = _Ego multus sim_ of the Sruti. [Sidenote: 2. The Universal soul, = Vìswátman.] It was at first known as _one_ and then as the _self_ or soul by the silent and innate intuition of the intellect, as it is declared in the Mandukya Upanishad II. 2, 5. तमेबैकंजानथआत्मानमन्यावाचो, बिमुञ्चथअमृतस्यैब सेतुः । मण्डूकं २ । २१५ । Max Müller says (A. S. Lit. p. 23 and p. 322): “The Átman was next conceived as the Spirit = air, _átmá_ and _anime_.” “That one breathed breathless by itself: other than it nothing since has been.” Thus says the Sruti (Müller p. 560). “This one Átman (atmos) fills, animates and pervades the whole”; as the poet sings “spreads unspent” throughout the infinity of worlds: “Which are but parts of one undivided whole whose body nature is, and God the soul.” (Pope). एकमेवाद्वितीयं ब्रह्म । रूपं रूपं प्रतिरूपं विभाति ॥ [Sidenote: 3. Called as _Tat_ = that] The inherent one of all ones “_to on ontwn_,” the unit of unities, the Ens of entities, the soul of the world “Viswátman” was yet without a name, nor did they know how to call him, than by the designation of _tat_ = “that,” which they say is expressive of the idea of Brahma तदिति ब्रह्मणोऽभिधानमुदाहृतं । Because says Váchaspati, the nature of the one _Om_, was unknown even to the learned बिदुषां परोक्षत्वाच्च तच्छब्दो ब्रह्मणो नाम; and therefore it was specified by the demonstrative pronoun _that_ “_tat_,” which sometimes preceded the एक as तदेकं &c. (Greek _to on_). The necessity of pronouncing _Om_ with _tat sat_ in the beginning of every Vedic rite, is strictly enjoined in Bhágavad-Gítá. ॐ तत्सदिति निर्द्देशो ब्रह्मनस्त्रिविधः स्मृतः । ब्राह्मणश्चैब बेदाश्च यज्ञाश्चबिहिताः पुरा । बैदिके कर्म्मणि तेषां प्रथमतो निर्द्देशः । इति तां बाचस्पतिः । [Sidenote: 4. The Impersonal and Personal God.]