Yet you do not know [the least thing] about what may happen tomorrow. What is the nature of your life? You are [really] but a wisp of vapor (a puff of smoke, a mist) that is visible for a little while and then disappears [into thin air].
For who [limited to human wisdom] knows what is good for man in his life, all the days of his vain life which he spends as a shadow [going through the motions but accomplishing nothing]? For who can tell a man what will happen [to his work, his treasure, his plans] under the sun after he is gone?