Kṛṣṇa says that "I am the origin of all births, everything." So the material world was not existing. This is insufficient. How you can say it is existing? Anything you see, material, it has got a date of birth. Who can deny it? Can you present anything material which was, which has no beginning? Everything has got beginning. So how you can say this material world has no beginning? This is nonsense.
Therefore hetumadbhir viniścitaiḥ. Hetu means "with reason," not like dogmatic obstinacy. You must have the beginning. Then, as soon as you, we, accept that this material world has had a beginning... The śāstra says it has beginning. Just like Brahma-sūtra, janmādy asya yataḥ (SB 1.1.1). Why it says, janmādy asya (SB 1.1.1)? Everything has beginning.
And we see from the śāstra how this material world has a beginning. There was first of all Mahavisnu. From Mahavisnu, these universes came out.
- yasyaika-niśvasita-kālam athāvalambya
- jīvanti loma-bilajā jagad-aṇḍa-nāthāḥ
- viṣṇur mahān sa iha yasya kalā-viśeṣo
- govindam ādi-puruṣaṁ tam ahaṁ bhajāmi
- (Bs. 5.48)
Before this universal creation, Kṛṣṇa took the form of Mahavisnu, and Mahavisnu's breathing period is the creation and annihilation. So long the breathing goes on, exhaling, that is the creation period; inhaling, the destruction, annihilation. So the whole cosmic manifestation is being maintained within the breathing period of Mahavisnu.