Thanks for the Ecclesiastes quote, Ecclesiastes is one of my favorite wisdom books, and a classic for any startup founder.
Just to add to your comment, I think the key to understanding the "meaningless" motif, and how the book works, is that the "meaningless" motif is used by the author to shut off every dead-end path, things that perhaps might be good things but good things which can't bear the weight of worship, things which can't in themselves give meaning or purpose to your life.
It's like a rat maze, with the author helpfully shutting all the paths, except the one path that matters, "the conclusion of the matter", the path of the "firmly embedded nails" on which you can stake your life, the path which is the duty of man, the path which is truly good and which will ultimately be rewarded.
Just to add to your comment, I think the key to understanding the "meaningless" motif, and how the book works, is that the "meaningless" motif is used by the author to shut off every dead-end path, things that perhaps might be good things but good things which can't bear the weight of worship, things which can't in themselves give meaning or purpose to your life.
It's like a rat maze, with the author helpfully shutting all the paths, except the one path that matters, "the conclusion of the matter", the path of the "firmly embedded nails" on which you can stake your life, the path which is the duty of man, the path which is truly good and which will ultimately be rewarded.