I think it's pretty clear that: 1) Civil Service and the ability to get 4 (F+H) tiles without bonuses is huge. Since these are riverside, they also give a gold, which is also good. 2) Civil Service is a medieval era tech, opening up the Patronage tree, which is useful. (it also opens up Commerce, which I'm yet to try). 3) Civil Service is far more expensive than any of its prerequisites, when you finish philosophy it could be 50 or more turns to research. 4) An early Great Scientist or Great Library can bulb Civil Service much earlier than any other approach will. The only question is: How fast do you need to build the great library? How fast can a city get a library up and running two scientists? Is Babylon's free GS at writing overpowering? Which is more efficient? The two options if you don't have the deluxe edition: 1) Great Scientist - this takes 17 turns of running 2 scientists. If you have enough food in your capital or second city, this is probably not a large hardship; 3 science compares reasonably well to non-bonus tile outputs. If you don't have 4-food tiles, you may need to run a food deficit to do this; it's probably not worth building a granary first. 2) Great Library - wonders are cheap compared to other stuff, but there's a chance you get beaten to it. The fact that the AI won't wait to research philosophy means you have to get the research side going as well. Aristocracy helps here, as does being Egypt.