Then I looked on all the works that my hands had made, and on the labor that I had expended on it: and, behold, all was vanity and like grasping the wind, and there was no profit under the sun.
All Commentaries on Ecclesiastes 2:11 Go To Ecclesiastes 2
Gregory of Nyssa
People who write in water are engaged in drawing the shapes of the letters in the liquid by writing with the hand, but nothing remains of the shape of the letters, and the interest in the writing consists solely in the act of writing (for the surface of the water continually follows the hand, obliterating what is written). In the same way all enjoyable interest and activity disappears with its accomplishment. When the activity ceases the enjoyment too is wiped out, and nothing is stored up for the future, nor is any trace or remnant of happiness left to the pleasure takers when the pleasant activity passes away. This is what the text means when it says “there is no advantage under the sun” for those who labor for such things, whose end is futility.