All the rivers run into the sea; yet the sea is not full; unto the place from where the rivers come, there they return again.
All Commentaries on Ecclesiastes 1:7 Go To Ecclesiastes 1
Ephrem The Syrian
AD 373
The waters that the earth drank on the first day were not salty. Even if these waters were like the deep on the surface of the earth, they were not yet seas. For it was in the seas that these waters, which were not salty before being gathered together, became salty. When they were sent throughout the entire earth for the earth to drink they were sweet, but when they were gathered into seas on the third day, they became salty, lest they become stagnant due to their being gathered together, and so that they might receive the rivers that enter into them without increasing. For the quantity that a sea requires for nourishment is the measure of the rivers that flow down into it. Rivers flow down into seas lest the heat of the sun dry them up. The saltiness [of the seas] then swallows up [the rivers] lest they increase, rise up and cover the earth. Thus the rivers turn into nothing, as it were, because the saltiness of the sea swallows them up. .
