Ecclesiastes 8:17
Then I beheld all the work of God, that a man cannot find out the work that is done under the sun: because though a man labour to seek it out, yet he shall not find it; yea further; though a wise man think to know it, yet shall he not be able to find it.
Solomon, the son of David and king in Jerusalem, wrote after his unsatisfying experience with wealth and luxury and idolatry when his heart was led away by his many wives. It belongs together with chapters 7 and 9 as the morning reading for September 21.
No man can fully discover or comprehend all of God's work done under the sun in the world, however diligently he labors to seek it out, and even though a wise man thinks to know it he shall not be able to find it. It sets forth the vanity of human life and the utter uselessness of all human pursuits apart from God. Its conclusion is that the whole duty of man is to fear God and keep His commandments.