The Lord is giving a genealogical synopsis of the universal population. Brahma is the original creature born out of the energy of the Supreme Lord known as Hiranyagarbha. And from Brahma all the seven great sages, and before them four other great sages, named Sanaka, Sananda, Sanatana, and Sanatkumara, and the fourteen Manus, are manifest. All these twenty-five great sages are known as the patriarchs of the living entities all over the universe. There are innumerable universes and innumerable planets within each universe, and each planet is full of population of different varieties. All of them are born of these twenty-five patriarchs. Brahma underwent penance for one thousand years of the demigods before he realized by the grace of Krsna how to create. Then from Brahma, Sanaka, Sananda, Sanatana, and Sanatkumara came out, then Rudra, and then the seven sages, and in this way all the brahmanas and ksatriyas are born out of the energy of the Supreme Personality of Godhead. Brahma is known as pitamaha, the grandfather, and Krsna is known as the prapita-maha, the father of the grandfather. That is stated in the Eleventh Chapter of the Bhagavad-gita. (Bg. 11.39)