(redacted names and ideas so the student can continue writing without needing to worry that someone would steal his/her idea - MFE)
The nice thing about your last "possible thesis" is that it's a statement that demands proof. No one can disagree with the "Virgil represents Human Reason" statement - it's an incontrovertible fact, not a theory that demands justification. Why write three pages arguing something that your reader agreed with after reading four words?
But your idea about _________ interests me; I can see areas where your reader could challenge you, and where you could rise to the challenge.
That's the purpose of the essay, ________: not to say something we already believe, but to make us believe something we didn't believe or hadn't seen before, even if it - like ___________ - was sitting in front of us the whole time.
In the last e-mail, I'd say the second "example" thesis is the stronger of the two: it's shorter and more direct while avoiding "listing-thesis syndrome." You don't necessarily want to spell everything out in your thesis...just the main points. After all, if we can see exactly how you're going to do it, there's no surprise or suspense motivating your reader to finish; he'll read your thesis, nod, and go home.
Think of yourself as a magician: the best parts of a trick (i.e., the things that separate a classic from a garden-variety illusion) aren't the introduction and ending, but everything between them. Your body paragraphs should enlighten and entertain, so don't spoil your surprise - pull off the trick by keeping us captivated throughout!