“To this Seven-vowelled god the candidate for initiation is sent by Christos, in the Pistis Sophia, a work earlier than St. John’s Revelation, and evidently of the same school.
“The (Serpent of the) Seven Thunders uttered these seven vowels”, but “seal up those things which the seven thunders uttered, and write them not”, says Revelation (10:4).
“Do ye seek after these mysteries?” inquires Jesus in Pistis Sophia (378).
“No mystery is more excellent than they (the seven vowels): for they shall bring your souls unto the Light of Lights” – i.e., true wisdom.
“Nothing, therefore, is more excellent than the mysteries which ye seek after, saving only the mystery of the Seven Vowels and their FORTY AND NINE Powers, and the numbers thereof.
In India, it was the mystery of the Seven FIRES and their forty-nine fires or aspects, or “the members thereof”, just the same.
These seven vowels are represented by the Swastika signs on the crowns of the seven heads of the Serpent of Eternity, in India, among esoteric Buddhists, in Egypt, in Chaldea, etc., etc., and among Initiates of every other country.
It is on the Seven zones of post mortem ascent, in the Hermetic writings, that the “mortal” leaves, on each, one of his “Souls” (or Principles); until arrived on the plane above all zones he remains as the great Formless Serpent of absolute wisdom – or the Deity itself.
The seven-headed serpent has more than one signification in the Arcane teachings. It is the seven-headed Draco, each of whose heads is a star of the Lesser Bear;
but it was also, and pre-eminently, the Serpent of Darkness (i.e., inconceivable and incomprehensible) whose seven-heads were the seven Logoi, the reflections of the one and first manifested Light – the universal LOGOS.”
H. P. Blavatsky
The Mark Of God: Understanding Your "I AM Presence" 