“During all these stages the Lunar Pitris have acted as the souls of the forms, brooding over them, later inhabiting them.
It is on the first-class Pitris that the heaviest burden of the work falls during the first three rounds. The second and third-class Pitris flow into the forms and work up by the first; the first prepare these forms by ensouling them for a time and then pass on, leaving for the tenancy of the second and third classes.
By the end of the first round the archetypal forms of the mineral world have been brought down, to be elaborated through the succeeding rounds, till they reach their densest state in the middle of the fourth round. “Fire” is the “element” of the first round.
In the second round the first-class Pitris continue their human evolution, only touching the lower stages as the human foetus still touches them today, while the second class, at the close of the round, have reached the incipient human stage.
The great work of the round is bringing down the archetypal forms of vegetable life, which will reach their perfection in the fifth round. “Air” is the second round “element”.
Annie Besant
The Mark Of God: Understanding Your "I AM Presence" 