What supports the earth?

Once upon a time, not that far from here, there was a small village, and at the end of the village there was a small hut in which there lived an old, wise man. One day, a lady from the village approached and called the old man out of his hut.

"Tell me", she said, "everything falls down, why does the earth itself not fall down?"

The old man answered, "Because it is supported by an elephant."

The lady did not need long to think, and asked, "But what supports the elephant?"

The old man looked at her intently and replied, "The elephant is standing on a tortoise," and since it was by now clear that this lady was not one to be satisfied easily, he quickly added, "and it is tortoises, all the way down."