Ecclesiastes 8:16-17

When I gave my mind to the knowledge of wisdom and to seeing the business which is done on the earth (and there are those whose eyes see not sleep by day or by night), Then I saw all the work of God, and that man may not get knowledge of the work which is done under the sun; because, if a man gives hard work to the search he will not get knowledge, and even if the wise man seems to be coming to the end of his search, still he will be without knowledge.