ABSTRACTThe usual description of Chinese mathematical astronomy as a fundamentally practical, empirical collection of techniques reflects not national character but a conscious choice at a certain point in history. The two great systems of the first century A.D. were necessarily founded upon and greatly conditioned by philosophical assumptions about the simple cyclical character of the celestial motions. Astronomers were forced to incorporate mediocre prediction methods for lunar eclipses and planetary motions, which their postulates were too crude to fit. Techniques of very high accuracy could have been discovered and used with no more sophisticated mathematics, but they could not have been assimilated to the formal character of Chinese astronomy as a whole. The dilemma was resolved over the next few centuries, not by astronomers' substituting new assumptions more conformable to the complexity of the phenomena, but by their becoming indifferent toward cosmology.