Joseph Epstein, one of the best essayists out there, on the relationship between facts and ideas:
The point (I don't say it is a fact or an idea) is that the more facts one has at one's command, the less is inspiration for ideas likely to arrive. Imagine the impressive ignorance of facts Rousseau required to come up with his two most famous ideas, those of the Noble Savage and of the Social Contract. Marx had Engels in Manchester supplying him with many of his facts for "Das Kapital," but given all the additional factual knowledge we have since acquired about industrial relations and the true interests of the working classes, it seems doubtful that even the always rage-ready Marx would be able to believe in the class struggle with the same certitude. Or, presented with the wretches of Enron, price-rigging, industrial spying and other corporate malfeasance, would Adam Smith still wish to argue on behalf of his Invisible Hand?
The most fertile ground for the formation of ideas, in other words, is one relatively barren of facts. As facts add up, ideas tend to go down. Facts, bloody damn facts, get in the way of conjecture, speculation, delightful mental footwork of all kinds. Facts, we say with a shrug, are facts.