大乘入道次第開決 1.102

1.102

天地別乎行潦者。天地即是大海異名。如言南溟北溟浡澥等。行潦乃是流水名也。以水流處小而且淺。與海異也。

Regarding "heaven and earth differ from flowing puddles": "heaven and earth" here is an alternative name for the great ocean, like speaking of the Southern Deep, Northern Deep, the Bohai Sea, and so forth. "Flowing puddles" refers to flowing water. Because the place where the water flows is small and shallow, it differs from the ocean.