Ecclesiastes 8:16 in the King James Version
When I applied mine heart to know wisdom, and to see the business that is done upon the earth: (for also there is that neither day nor night seeth sleep with his eyes:)
Context
15 Then I commended mirth, because a man has no better thing under the sun than to eat, to drink, and to be joyful: for that will accompany him in his labor all the days of his life which God has given him under the sun.
16 When I applied my heart to know wisdom, and to see the business that is done on the earth (even though eyes see no sleep day or night),
17 then I saw all the work of God, that man can’t find out the work that is done under the sun, because however much a man labors to seek it out, yet he won’t find it. Yes even though a wise man thinks he can comprehend it, he won’t be able to find it.