Why is the Teacher so depressed? When I was a teenager, the existential angst felt natural and obvious. Returning to the text as an adult who will be teaching it in class, I felt less secure. It seemed almost like an American arthouse film from the 70s, with everyone railing against an unspecified “phoniness” to which there nonetheless seemed to be no alternative. Compared to what is everything “vanity”? This is the only world, the only point of reference we have — what would it even mean for it to be meaningless?
And then it hit me: this isn’t the only point of reference, because this very “secular” text makes strategic reference (unlike Esther, for example) to God. Ecclesiastes is the lament of a man who can never be God, who lives in a world that God set up to remind you that you can never be God. The more he seeks for power, wisdom, and permanence, the more obvious it becomes that he can never be as all-powerful, as all-knowing, as eternal as God is. Indeed, the more he pushes the boundaries of what is possible for human beings — it is no accident that this text is traditionally attributed to Solomon, the pinnacle of human achievement in the Hebrew biblical tradition — the more reminders he gets.
Hence the continual advice that we should eat and drink and enjoy our toil. It’s not that those things are great or enjoyable. We are not dealing with an edifying message that we should “live for today.” The reason we should embrace fleeting pleasures and make the most of our subordination is that then we will not have to live with any painful reminders that we are not God.
In The Prince of This World, I claim that the political theology of the Hebrew Bible sets up a rivalry between God and the earthly ruler, and Ecclesiastes is arguably the only place that we see that rivalry from the first-person perspective of the ruler himself. Hence if Pharaoh is the primal root of the figure of the devil as God’s permanently humiliated rival, the Teacher of Ecclesiastes is the root of the philosophical despair of Milton’s devil, who knows for a fact that he can never defeat or replace God, but nonetheless feels compelled to keep trying — because for all his diagnoses of vanity, we never hear that the Teacher follows his own advice and abdicates the throne to become a simple laborer.
No one who has seized upon that hopeless hope can ever give up the quest to be God. Once that insane, impossible thought has entered one’s mind, there is no choice but to embrace the futility and humiliation and pain as a protest that becomes its own pleasure and satisfaction. Better to rule in hell than to serve in heaven — and better a world in which I can cast God as an illegitimate, arbitrary despot (in the very canon of Scripture!) than a world in which I cannot be God.
An und für sich 
I wonder if there’s some resonance with this and Foucault’s discussion of the relation between care for the self and knowing thyself in his Technologies of the Self lecture. That is, would the Teacher’s recognition that he is not God be similar to the relation between concern for the self and the delphic warning to recognize that one is not god (i.e. to know oneself) before approaching. So what we have in Ecc is a similar binary relation between the Greek concern for self and knowing oneself…?