The sages of the Midrash (rabbinic interpretive commentary) asked a question that seems simple but opens onto infinity: where does all the water in the rivers go?
Every river on earth flows toward the sea. The Jordan, the Nile, the Euphrates — all of them pour their waters into the great oceans without ceasing, day after day, year after year, century after century. And yet the oceans never overflow. Where does all that water go?
Bereshit Rabbah (ch. 13, section 9) provides the answer. God created a system of circulation at the very beginning of the world. The waters of the rivers flow into the ocean. The ocean's waters are drawn up into the clouds by the heat of the sun. The clouds carry the water over the land and release it as rain. The rain fills the springs and streams, and the streams become rivers, and the rivers flow back to the ocean. The cycle never ends.
Kohelet Rabbah (1:7, section 3) connects this to the verse in Ecclesiastes: "All the rivers flow into the sea, yet the sea is not full; to the place from which the rivers flow, there they return again" (Ecclesiastes 1:7). King Solomon, the rabbis said, understood the water cycle thousands of years before modern science described it.
But the sages saw more than science in this phenomenon. They saw a parable for Torah. Just as water circulates endlessly from sea to cloud to rain to river and back again, so Torah flows from God to Israel and back to God through prayer and study. The cycle of wisdom, like the cycle of water, never runs dry.