Verse 18. And - As when a great mountain falls, by an earthquake or inundation, it moulders away like a fading leaf, (as the Hebrew word signifies) and as the rock, when by the violence of winds or earthquakes it is removed out of its place, and thrown down, is never re-advanced: and as the waters by continual droppings, wear away the stones, so that they can never be made whole again: and as thou wastest away, by a great and violent inundation, the things which grow out of the dust of the earth, herbs, and fruits, and plants, which once washed away are irrecoverably lost; in like manner, thou destroyest the hope of man: when man dies, all hope of his living again in this world is lost.
Verse 20. Prevailest - When once thou takest away this life, it is gone forever. Sendest - To his long home.
Verse 21. Knoweth not - Either is ignorant of all such events: or, is not concerned or affected with them. A dead or dying man minds not these things.