Rabbi Eliezer and Rabbi Yehoshua were aboard a ship when a storm drove them far out into the open ocean. The wind pushed them into waters no Jew had reason to visit. Rabbi Eliezer, studying the strange current around them, said to his companion, "We must have been driven here for a reason. Let us bring back a proof of where we have been."
The two rabbis took an empty cask and filled it with seawater from the farthest point they reached. When the storm abated and the ship returned, they carried the cask with them to land. In time they found themselves summoned to Rome by the emperor Hadrian (Adrianus, as the Exempla names him), who was known for probing Jewish scholars with questions about the natural world.
Hadrian asked about the ocean. Why does the sea not overflow? Rivers pour into it continually from every land, and yet the level of the waters remains the same. What happens to all the water?
The two rabbis produced their cask. They poured water into it from a vessel, then poured more, and more. The cask did not overflow. The water they had drawn from the deep ocean kept absorbing whatever was poured into it. The level inside the cask never rose. Whatever they added, the ocean-water swallowed.
"This is why the sea does not overflow," they told the emperor. "Its own waters drink what is poured into them." Whether the demonstration was physics or miracle is never entirely clear in the Exempla's brief account. What is clear is that Rabbi Eliezer and Rabbi Yehoshua had been driven off course precisely so that Rome would one day have its answer. A detour by storm is sometimes the shortest path to a question you did not yet know would be asked.