I saw every work of God, and that a man is unable to comprehend the work that is done under the sun. Despite his efforts to search it out, he cannot find its meaning; even if the wise man claims to know, he is unable to comprehend.
KJV
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].
ASV
then I beheld all the work of God, that man cannot find out the work that is done under the sun: because however much a man labor to seek it out, yet he shall not find it; yea moreover, though a wise man think to know it, yet shall he not be able to find it.