word I will briefly tell thee—­it is Om.  This syllable means the (inferior) Brahman and the supreme (Brahman).  Whoever knows this syllable obtains whatever he wishes.”  And in the Pras’na-Upanishad the saint Pippalada says to Satyakama:  “The supreme and the inferior Brahman are both the word Om; hence the wise follow by this support the one or the other of the two.  If he meditates upon its one letter (a) only, he is quickly born on the earth; is carried by the verses of the Rig Veda to the world of man; and, if he is devoted there to austerity, the duties of a religious student and faith, he enjoys greatness.  But if he meditates in his mind on its two letters (a and u), he is elevated by the verses of the Yajur Veda to the intermediate region; comes to the world of the moon and, having enjoyed there power, returns again (to the world of man).  If, however, he meditates on the supreme spirit by means of its three letters (a, u, and m) he is produced in light in the sun; as the snake is liberated from its skin, so is he liberated from sin.”  According to the Mandukya-Upanishad the nature of the soul is summarized in the three letters a, u, and m in their isolated and combined form—­a being Vaiswanara, or that form of Brahman which represents the soul in its waking condition; a, Taijasa, or that form of Brahman which represents it in its dreaming state; and m, Piajna, or that form of Brahman which represents it in its state of profound sleep (or that state in which it is temporarily united with the supreme spirit); while a, u, m combined (i.e., Om), represent the fourth or highest condition of Brahman, “which is unaccountable, in which all manifestations have ceased, which is blissful and without duality.  Om therefore, is soul, and by this soul, he who knows it, enters into (the supreme) soul.”  Passages like these may be considered as the key to the more enigmatic expressions used; for instance, by the author of the Yoga philosophy where, in three short sentences, he says his (the supreme lord’s) name is Pranava (i.e., Om); its muttering (should be made) and reflection on its signification; thence comes the knowledge of the transcendental spirit and the absence of the obstacles (such as sickness, languor, doubt, &c., which obstruct the mind of an ascetic).  But they indicate, at the same time, the further course which superstition took in enlarging upon the mysticism of the doctrine of the Upanishads.  For, as soon as every letter of which the word Om consists was fancied to embody a separate idea, it is intelligible that other sectarian explanations were grafted on them to serve special purposes.  Thus, while Sankara, the great theologian and commentator on the Upanishads, is still contented with an etymological punning by means of which he transforms a into an abbreviation of apti (pervading), since speech is pervaded by Vaiswanara; u into an abbreviation of utkartha (superiority), since Taijasa is superior to Vaiswanara; and m into