Missionary activity presents unique problems for theories of alterity. By definition the missionary is attempting not only to introduce something new to the “other” society but to present it in a way that makes the new acceptable. Early modern missionaries in China are a useful test-case for examining how cross-cultural exchange occurs. It cannot be simply a matter of misunderstanding or deception and, certainly not, of material advantage. Conversion implies change but change may be development as well as rejection. Western humanism and theological developments provided a conceptual armory well exploited by the Jesuit missionaries and appreciated by the “Confucian Christians”.