Ideas are important in human history. They shape the mental or cultural worlds that people everywhere inhabit, and they often influence behavior as well. Many of the ideas developed or introduced during the early modern era have had enormous and continuing significance in the centuries that followed. The Western Hemisphere was solidly incorporated into Christendom. A Wahhabi version of Islam remains the official faith of Saudi Arabia into the twenty-first century and has influenced many contemporary Islamic revival movements, including al-Qaeda. Modern science and the associated notions of progress have become for many people something approaching a new religion.

Accompanying the development of these ideas has been a great deal of cultural borrowing. Filipinos, Siberians, and many Native American peoples borrowed elements of Christianity from Europeans. Numerous Asian and African peoples borrowed Islam from the Arabs. North Indian Sikhs drew on both Hindu and Muslim teachings. Europeans borrowed scientific and medical ideas from the Islamic world and subsequently contributed their own rich scientific thinking to the entire planet.

In virtually every case, though, borrowing was selective rather than wholesale, even when it took place under conditions of foreign domination or colonial rule. Many peoples who appropriated Christianity or Islam certainly did not accept the rigid exclusivity and ardent monotheism of more orthodox versions of those faiths. Elite Chinese were far more interested in European mapmaking and mathematics than in Western medicine, while Japanese scholars became fascinated with the anatomical work of the Dutch. Neither, however, adopted Christianity in a widespread manner.

Borrowing was frequently the occasion for serious conflict. Some objected to much borrowing at all, particularly when it occurred under conditions of foreign domination or foreign threat. Thus members of the Taki Onqoy movement in Peru sought to wipe out Spanish influence and control, while Chinese and Japanese authorities clamped down firmly on European missionaries, even as they maintained some interest in European technological and scientific skills. Another kind of conflict derived from the efforts to control the terms of cultural borrowing. For example, European missionaries and Muslim reformers alike sought to root out “idolatry” among native converts.

To ease the tensions of cultural borrowing, efforts to “domesticate” foreign ideas and practices proliferated. Thus the Jesuits in China tried to point out similarities between Christianity and Confucianism, and Native American converts identified Christian saints with their own gods and spirits. By the late seventeenth century, some local churches in central Mexico had come to associate Catholicism less with the Spanish than with ancient pre-Aztec communities and beliefs that were now, supposedly, restored to their rightful position.

The pace of global cultural borrowing and its associated tensions stepped up even more as Europe’s modern transformation unfolded in the nineteenth century and as its imperial reach extended and deepened around the world.