In the poetic books of the Bible, structure and repetition are significant. In this passage, the double commands at the beginning and end (verses 1-2 and 6) and the repetition of the phrase "do not know" calls our attention to the key teaching of the Preacher here.
sermons | study
These are sermons preached during our Sunday worship services. (Recordings were not always successful, so there are gaps in the postings.)