According to the medieval Western theory of taxation, a king could levy taxes only with the consent of taxpayers.On the contrary, an ancient Chinese emperor levied taxes and corvee, dispensing with people's consent.In order to effectively reign over society, however, monarchs, officials and men of letters in all dynasties made a lot of explanations and illustrations to demonstrate legitimacy of emperors' levying taxes, thus constructing a basic theory of taxation endemic to China.that is, a theory about an emperor's possession of all land and people under the heaven.The great difference between Chinese and Western theories of taxation was caused by their own social conditions, including a contrast of tax-gatherers' and tax-payers' status and power, and different Chinese and Western cultures and social universal ideas.