Matthew Poole and continuators on Ecclesiastes 8:6

6 Because to every purpose there is time and judgment , therefore the misery of man is great upon him.

There is a fit way and season for the happy accomplishment of every business which a man designeth or undertaketh to do, which is known to God, but for the most part hidden from man, as is implied and may be gathered from the following words. See the Notes on Ch. 3. 1.

Because there are very few who have that wisdom which is necessary to discern this, as was now said, v. 5. and most men do by their ignorance and loss of opportunities deprive themselves of many advantages, and expose themselves to manifold miseries.