For my weekly quiet time this Sabbath, I studied Ecclesiastes 10.
I encountered a theme in Ecclesiastes 10:8-11 that occurs throughout Ecclesiastes: that wisdom can make our life better, and yet the world is not fool-proof. Accidents can still happen, even to the wise. A person may be digging a pit, tearing down a wall, quarrying stones, or cleaving wood, and he is suddenly injured or killed in his work. Granted, some difficulties with work are solved by good old practical wisdom: a wise person will chop wood after he sharpens the blade of his ax, for example, rather than chop with a dull blade. But wisdom does not solve everything: a man may be an expert snake-charmer, for instance, and yet his snake-charming will not help him if the snake bites him out of the clear blue sky, before the man even know what's what!
Jewish interpretations that I read (or read about)---such as Ecclesiastes Rabbah, Rashi, Jarchi, and targumim---tried to interpret Ecclesiastes 10:8-11 in an ethical sense. There are places in Scripture in which a man falling into a pit he has dug refers to punishment for sin: a man tries to hurt somebody by digging a pit for his potential victim to fall into, and, instead, the digger of the pit falls into it (see Psalm 7:14-16; 9:15-16; Proverbs 26:27)! Rabbis applied Ecclesiastes 10's reference to tearing down a wall to transgressing the words of the sages, and its passage about quarrying stones to Jewish students removing themselves from the study of the Torah. As is often the case with religious interpretations of Ecclesiastes, Jewish interpreters attempted to reconcile Qoheleth's belief in a chaotic world with their own view that the world is a place that's manageable because it is governed by a good God who consistently rewards righteousness and punishes wickedness.
I don't say this often, but Calvary Chapel preacher Bob Davis' sermon on Ecclesiastes 10 was actually pretty good, aside from the anti-Muslim comment he throws in (click on Ecclesiastes 10 to listen). Ecclesiastes 10:1 says that dead flies corrupt good ointment, and a little folly can outweigh much wisdom. Davis interpreted this verse to mean that it only takes one bad decision to dramatically and negatively affect a person's life, however wise he may have lived for the majority of his time. A sexual abuser, for example, may be sorry for her deed and have God's forgiveness, but she will experience legal consequences for the rest of her natural life. A person who normally does not party may go to a get-together and get drunk one night, and he ends up killing people in an automobile accident. One bad decision can have life-changing effects. That could be why many interpreters believe that Ecclesiastes 10 is saying that wise people are careful and moral: sure, wisdom is not fool-proof, but being careful can obviate problems that carelessness or immorality can create.
Ecclesiastes 10 also offers political commentary. Qoheleth is sort of a political elitist, for he bemoans the poor and the foolish being elevated, even as the rich and the nobles are brought down. In the HarperCollins Study Bible, Raymond Van Leeuwen identifies a similar elitism in Proverbs 26:1; 30:21-23; and Isaiah 3:4-5. Ecclesiastes 10:16-17 may offer Qoheleth's rationale for his elitism: a king who is a child is continually partying with his princes, which clouds his judgment, whereas a noble king only parties with them at appropriate times. But, soon after Qoheleth criticizes certain types of kings, he goes on to say that we shouldn't criticize the king in our thoughts or in private, for the king may learn that we have a bad opinion of him. This is Qoheleth's practical wisdom: we may not like a king, but the king is more powerful than we are and can hurt us, and so we should exercise caution.
Qoheleth's elitism makes me think: elites do not necessarily govern well, for there are many that have oppressed people, and the Bible criticizes oppression in a number of places. But non-elites that assume power can themselves be oppressive, and their new-found power can go to their heads. Moreover, non-elites' lack of experience in governing may not do people much good.