अकारो विष्णुरुद्दिष्टः उकारस्तु महेश्वरः ।
मकारउच्यते ब्रह्मा प्रणबेन त्रयोमतः ॥
So also the Bhagavad Gitá. VIII. 13.
Here the two halves of the circle उ comprise Vishnu and Siva as joined in the bipartite body of Hari Hara alias Hara Hari, adored by the dualists called द्वैतवादिनः, or more fully as हरिहराद्वैतवादिनः and Brahmá the god of Manu, is placed in the circlet above the great circle of his created world. We need but hint to our readers in this place, to observe how the original word Om or Ov and One developed itself into the existing faith of trinity. The Tántrica Sivites however place their god Siva in the upper semicirclet formed by म = m the initial of Maheswara (महेश्वर), and say:—
ॐकारपूर्ब्बमुद्धृत्य ब्रह्मबिष्णुशिबात्मकं ।
अधोबिन्दु ब्रह्मबिष्णुरुर्द्धबिन्दु शिबात्मकं ॥
This is more reasonable to believe from both the letter m’s and its god Siva’s amalgamation with the early Aryan duality to form the present faith of triality at a much later period.
4. Om the Tetrad. We next see a further progress of Om in its development from the triliteral to a quadriliteral form, by its assumption of a crescent or half circlet (कुण्डली) according to the Tantra, or a half Mátrá (अर्द्ध मात्रा) of the Vedánta. The Tantra says तदूर्द्ध कुण्डलीकारा शक्तिः । The Maitrí Upanishad mentions only of the three Mátrás of Om (Ch. vi Sec. 3).
“But the Mundak Upanishad” says Weber, “refers to the half Mátrá (mora), to which the word Om here appearing in its full glory, is entitled in addition to its three Mátrás (morae) a. u. m. This is evidently a later addition by some one who did not like to miss the mention of the subject in the Atharvana Upanishad in which it occurs.” p. 160. Again says he—“The Mándukya Upanishad which treats of the three and half Mátrás of the word Om, is to be looked upon as the real Mándukya, all the rest is the work of the Gaudapáda, whose pupil Govinda was the teacher of Sankaráchárya about the seventh century A. D.”
5. Om the Pentad. We find next a quinquiliteral figure of Om in its component parts of the three mátrás, m, and the bindu or चन्द्र बिन्दु the fifth.