This may be understood either,
1. By way of opposition, the waters go or flow out of the sea, and return thither again, Ecclesiastes 1:7; and a lake or river sometimes decayeth, and drieth up, but afterwards is recruited and replenished. But man lieth, &c., as it follows. Or,
2. By way of resemblance; As waters, i.e. some portion of waters, fail from the sea, being either exhaled or drawn up by the sun, or received and sunk into the dry and thirsty earth, or overflowing its banks; and as the flood, or a river, or a pond (for the word signifies any considerable confluence of waters) in a great drought decayeth, and is dried up; in both which cases the selfsame waters never return to their former places; so it is with man. Or thus, As when the waters fail from the sea, i.e. when the sea forsakes the place into which it used to flow, the river, which was fed by it, Ecclesiastes 1:7, decayeth and drieth up, without all hopes of recovery; so man, when once the fountain of his radical moisture is dried up, dies, and never revives again.