For who knoweth what is good for man in this life,
all the days of his vain life which he spendeth as a shadow?
for who can
tell a man what shall be after him under the sun?
Ecclesiastes 6:12
"MAN at his very best is only man;.... In part, he is but red earth, as 
Adam was when he came fresh from
his Maker’s hand.
As man is as light as vanity itself, Solomon urges that it is idle and
vain for him to attempt to contend with God. He puts it thus in the 10th
verse, “Neither may he contend with Him that is mightier than he.”
---It
is always unwise to contend with one who is mightier than yourself; but
when the disparity is so great as between man and God, — the creature of
an hour and the self -existent Creator, the poor feeble worm called man
and the almighty invincible God, — you see at once what folly it is
even to think of battling with Him."
Charles Spurgeon