Ambrose of Milan

With reference to the natural sense, you find it said in Ecclesiastes, "I made for myself pools of water to water from them a flourishing woodland." And do not be concerned that he said "pools" instead of "a well," because Moses said "the Well of Room-enough." For the man who has transcended this world with a pious mind is freed of all care and anxieties. There Ecclesiastes says "pools" with reason, for he sees that there is no abundance under the sun, but if anyone wishes to abound, let him abound in Christ. …

On Isaac and the Soul ↗

Jerome

"I constructed pools from which to irrigate a grove of young trees. "The wood in glades and in forests, which is not fruit-bearing, are not nourished by rain from the sky, not by such rain waters but by water which is collected in pools from rivers. Even low-lying Egypt is situated low in the land like a vegetable patch, and is irrigated by waters, which come from Ethiopia. But the Promised Land which is mountainous and raised up waits for timely or late-coming rain from the sky.

Commentary on Ecclesiastes ↗

Bonaventure

And because these things needed to be irrigated, he therefore adds: "And I built for myself pools of water," that is, places in which there is a collection of waters; and this, so that "I might irrigate the forest of sprouting trees," namely through irrigation, because it is said in Job 12: "If he withholds the waters, all things will be dried up." Such pools were necessary in the land of promise on account of the scarcity of water; Deuteronomy 11: "The land which you shall enter to possess is mountainous and level, awaiting rains …

Commentary on Ecclesiastes, Chapter 2 ↗