To give your essay, book, etc., a compelling title and also help your reader have a fulfilling experience with your work, choose a clause whose words come from your text itself, preferably somewhere deep into the work.  I have found that choosing my title first causes my writing to be stilted and uninspired - I am writing to fulfill the title instead of express what I want to - and almost never results in a good product.  Conversely, picking out a phrase or an allusion from a phrase makes both the title catchy and the text self-fulfilling and, therefore, more enjoyable for the reader.