These are really collective names for the various classes of monads, each single prajapati representing also the spiritual-intellectual hierarch of his own particular hierarchy or class of monads. Hence the meaning of prajapati as lord or parent of offspring -- the ten classes of monads corresponding each to its own proper prajapati. Further the prajapatis are the parents of the seven or ten manus. The Puranic myths with their genealogies of the seven prajapatis, rishis, or manus are "but a vast detailed account of the progressive development and evolution of animal creation, one species after the other" (SD 2:253).
"The whole personnel of the Brahmanas and Puranas -- the Rishis, Prajapatis, Manus, their wives and progeny -- belong to that pre-human period. All these are the Seed of Humanity, so to speak. It is around these 'Sons of God,' the 'Mind born' astral children of Brahma, that our physical frames have grown and developed to what they are now. For, the Puranic histories of all those men are those of our Monads, in their various and numberless incarnations on this and other spheres, events perceived by the 'Siva eye' of the ancient Seers, (the 'third eye' of our Stanzas) and described allegorically. Later on, they were disfigured for Sectarian purposes; mutilated, but still left with a considerable ground-work of truth in them. Nor is the philosophy less profound in such allegories for being so thickly veiled by the overgrowth of fancy" (SD 2:284).

These are really collective names for the various classes of monads, each single prajapati representing also the spiritual-intellectual hierarch of his own particular hierarchy or class of monads. Hence the meaning of prajapati as lord or parent of offspring -- the ten classes of monads corresponding each to its own proper prajapati. Further the prajapatis are the parents of the seven or ten manus. The Puranic myths with their genealogies of the seven prajapatis, rishis, or manus are "but a vast detailed account of the progressive development and evolution of animal creation, one species after the other" (SD 2:253).
"The whole personnel of the Brahmanas and Puranas -- the Rishis, Prajapatis, Manus, their wives and progeny -- belong to that pre-human period. All these are the Seed of Humanity, so to speak. It is around these 'Sons of God,' the 'Mind born' astral children of Brahma, that our physical frames have grown and developed to what they are now. For, the Puranic histories of all those men are those of our Monads, in their various and numberless incarnations on this and other spheres, events perceived by the 'Siva eye' of the ancient Seers, (the 'third eye' of our Stanzas) and described allegorically. Later on, they were disfigured for Sectarian purposes; mutilated, but still left with a considerable ground-work of truth in them. Nor is the philosophy less profound in such allegories for being so thickly veiled by the overgrowth of fancy" (SD 2:284).