I've been playing civ4 since the day vanilla came out, and now I am playing Warlords successfully at the monarch level. I am still not sure what real purpose the culture slider plays? Obviously it is necessary in a culture victory. I have also used it for a turn or two if a war has drawn out to long. What other uses does it actually have? Does anyone have an effective strategy [effective at higher levels] that demands a large proportion of income to be spent on culture?