Long, long ago I was talking with one Arya-samaji friend. So he did not believe that a lotus stem can grow on the navel of Visnu and there is Brahma born. Everyone says like that, “Mythology.” It is not mythology; it is fact. So I asked him that “Here we see one coconut tree, and about sixty feet above, there is coconut and there is water, there is pulp, and it is being carried from the ground. Where is the pipe? Where is the pump? How the water is there within the coconut? Can you explain?” So he could not explain. And I said that “Even in material things which is in front of you, you cannot explain. How you will explain the spiritual position? How the lotus grown from the navel of…?” Therefore it should be accepted as inconceivable. Acintyah khalu ye bhava na tams tarkena yojayet [Mahabharata, Bhisma parva 5.22]. Don’t try to argue; it is foolishness. It is inconceivable.

From Srila Prabhupada’s lecture on Srimad-Bhagavatam 5.5.31 — November 18, 1976, Vrndavana