In the Fourth Stanza, the "Sons of the Fire-Mist" are children of the rays of the "Third Creation or Logos," as H.P. Blavatsky explained in her Secret Doctrine Commentary 2:39. The seven Primordial "Sons of the Fire" are born from the 3rd Logos and replicate themselves in each stage of the descent into matter. They are the "seven primordial logoi" as the Central Suns at the head of their universal solar systems, per Fundamentals on page 527. Gradually, the seven Sons of Fire become the seven Sons of Earth. The term "fire" means "a deity who presides over Time." This fire is the same as the "invisible and fiery" germ in The Secret Doctrine 1:12. It is this fire that brings Time into existence. As H.P. Blavatsky stated in the Secret Doctrine Commentary 2:10, "Time and Space" begin with the 3rd Logos. Time begins for two reasons: 1) the space between two moments can now be measured in terms of the central point blazing across the darkened backdrop 2) the light ray of the 3rd Logos possesses a certain speed as it blasts away from the plane of the immaculate white disk.
Naturally, there are many types of "Fire" in The Secret Doctrine. The "first" and "purely Formless and Invisible Fire" is "concealed in the Central Spiritual Sun" and is spoken of as "triple." This refers to the immaculate white disk, the dull black ground, and the central point within a Central Sun. But the second type of fire is "Septenary, throughout both the Universe and our Solar System." This septenary universe is the secondary universe of the Mundane Egg. It includes the cosmic suns (Central, Polar, and Equatorial) reigning over their respective solar systems. This is an example of H.P. Blavatsky's "triad" branching off into the seven cosmical principles in The Secret Doctrine 1:18.
H.P. Blavatsky used the term "Primordial" to signify a ray from the first "Sacred Four" or the "Tetraktis" (distinct from the "universal ONE" because the Tetraktys is only ten-fold, not twelve-fold). The "Primordial" fire proceeds from the Father-Mother and so includes the Central Spiritual Sun (which contains the seven cosmical principles enfolded within itself) in combination with the central point, the dull black ground, and the immaculate white disk.
This "Sacred Four" generates more rays; these rays infuse the "manifested Quaternary and the Seven" with the life-force of their "Mother alone," the "immaculate Virgin-Mother" who is "overshadowed, not impregnated, by the Universal MYSTERY." In this reference, H.P. Blavatsky is not referring to the so-called independent Father and Mother prior to their union as Father-Mother with the first vibration of the potential point after the close of the Maha-Manvantara. Just as there are two darknesses and two lights, there are two mothers. This second mother is the Space in which the ray from the Central Sun falls into the womb of our Solar Sun. She is Aditi, the "mother of Marttanda (the sun), the Deva-matri--'Mother of the gods,'" per The Secret Doctrine 1:527. It is these "gods" to whom she gives birth during the Maha-Manvantara that die with the close of the Great Age. Under the rule of these "gods," the "manifested Quaternary" pertains to the four-fold realms under the jurisdiction of the Solar Sun in Cosmic Kama. The "Seven" applies to the seven planets of a solar system.
Sources:
H.P. Blavatsky, The Secret Doctrine (Pasadena: Theosophical University Press, 2019).
H.P. Blavatsky, Secret Doctrine Commentary (Pasadena: Theosophical University Press, 1994).
G. de Purucker, Fundamentals of the Esoteric Philosophy (Pasadena: Theosophical University Press, 1979).
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