He had eight sons born to him before he renounced the world.

The reason why the eight sons appear is twofold. First, to prove what Mañjuśrī says about what happened in the remote past, namely, that he was none other than the master of Torch Burner (Dīpaṃkara), [that is, Fine Luster (Varaprabha)], and that Torch Burner was in turn the master of Śākyamuni. As such, there cannot be anything false in what Mañjuśrī has said. Second, speaking in reverse, [it suggests that] one’s longevity [makes one] gradually open up one’s eyes.