“They are all seven-headed, the dragons and serpents of antiquity – “one head for each race, and every head with seven hairs on it”, as the allegory has it.
Aye, from Ananta, the Serpent of Eternity which carries Vishnu through the Manvantara, from the original Sesha, whose seven heads become “one thousand heads” in Puranic fancy, down to the seven-headed Akkadian Serpent.
This typifies the Seven principles throughout nature and man; the highest or middle head being the seventh.
The seven-headed or septenary DRAGON-LOGOS had been in course of time split up, so to speak, into four heptanomic parts or twenty-eight portions.
Each lunar week has a distinct occult character in the lunar month; each day of the twenty-eight has its special characteristics; as each of the twelve constellations, whether separately or in combination with other signs, has an occult influence either for good or for evil.
This represents the sum of knowledge that men can acquire on this earth;
yet few are those who acquire it, and still fewer are the wise who get to the root of knowledge symbolized by the great Root Dragon, the spiritual LOGOS of these visible signs.
But those who do, receive the name of “Dragons”, and they are the “Arhats of the Four Truths of the 28 Faculties”, or attributes, and have always been so called.”
H. P. Blavatsky
The Mark Of God: Understanding Your "I AM Presence" 