Here's a prophet who is viewing the world and its relationship to its Creator coming from the Jewish understanding that there is no afterlife to speak of. As my Jewish friend described his understanding, they will go to "the bosom of Abraham" and they have no special knowledge of what awaits them there.
So "the Preacher" as he calls himself is trying to puzzle out the reasons and results of living. The result is what I think is the most "sophisticated" book of the Bible - he's world-weary, wise and has it all figured out.
This statement originally caught my eye
Every man also to whom God has given wealth and possessions and power to enjoy them, and to accept his lot and find enjoyment in his toil -- this is the gift of God. For he will not much remember the days of his life because God keeps him occupied with joy in his heart. (Eccl 5:19-20)
I took it out of context first, seeing the second line as a nice motto for a rich interior life, but I think instead that it means the contentment that comes with the "wealth and possessions and power to enjoy" will make his life smooth. We all live awfully smooth lives, when you think about it.
Read it in its KJV language or in the Revised Standard Version.