What does Psalm 103:16 mean?

Continuing his thought about the frailty and brevity of human life, David notes how the wind passes over the grass and withers it. Not a trace of the grass remains after the wind tears it down. Isaiah 40:6–8 carries the same thought by stating that "all flesh is grass, and all its beauty is like the flower of the field." Both the grass and the flower wither and fade when the Lord blows on it.

In dry climates a scorching wind often dries up grass and flowers and leaves no trace of them. Human life may span a century, but the years pass quickly and death comes inevitably, leaving only memories. The apostle James compared the rich to grass that succumbs to the rays of the scorching sun. He concludes: "So also will the rich man fade away in the midst of his pursuits" (James 1:11). He also compares human life to a mist that appears for a brief time and then vanishes (James 4:14). In view of life's brevity and uncertainty, James underscores the importance of living every day according to the Lord's will (James 4:15).