Shrimad Bhagavad Gita As It Is -Shri Shrimad A.C Bhaktivedanta Swami Prabhupada
The Opulence of the Absolute
Chapter 10: Verse-6
maharsayah sapta pürve catväro manavas tathä
The seven great sages and before them the four other great sages and the Manus [progenitors of mankind] come from Me, born from My mind, and all the living beings populating the various planets descend from them.
The Lord is giving a genealogical synopsis of the universal population. Brahmä is the original creature born out of the energy of the Supreme Lord, who is known as Hiranyagarbha. And from Brahmä all the seven great sages, and before them four other great sages, named Sanaka, Sananda, Sanätana and Sanat-kumära, and the Manus, are manifested. 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. Brahmä underwent penance for one thousand years of the demigods before he realized by the grace of krsna how to create. Then from Brahmä came Sanaka, Sananda, Sanätana and Sanat-kumära, 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. Brahmä is known as Pitämaha, the grandfather, and krsna is known as Prapitämaha, the father of the grandfather. That is stated in the Eleventh Chapter of the 
- mahä-rsayah=the great sages; sapta=seven; pürve=before; catvärah=four; manavah=Manus; tathä=also; mat-bhäväh=born of Me; mänasäh=from the mind; jätäh=born; yesam=of them; loke=in the world; imäh=all this;prajäh=population.
- Bhagavad-gita 11.39