Upon the industrial side, it is impossible, I think, to exaggerate the influence of travel, exploration and new commerce which fostered a romantic sense of adventure into novelty; loosened the hold of traditional beliefs; created a lively sense of new worlds to be investigated and subdued; produced new methods of manufacture, commerce, banking and finance; and then reacted everywhere to stimulate invention, and to introduce positive observation and active experimentation into science. The Crusades, the revival of the profane learning of antiquity and even more perhaps, the contact with the advanced learning of the Mohammedans, the increase of commerce with Asia and Africa, the introduction of the lens, compass and gunpowder, the finding and opening up of North and South America--most significantly called The New World--these are some of the obvious external facts. Contrast between peoples and races previously isolated is always, I think, most fruitful and influential for change when psychological and industrial changes coincide with and reinforce each other. Sometimes people undergo emotional change, what might almost be called a metaphysical change, through intercourse. The inner set of the mind, especially in religious matters, is altered. At other times, there is a lively exchange of goods, an adoption of foreign tools and devices, an imitation of alien habits of clothing, habitation and production of commodities. One of these changes is, so to speak, too internal and the other too external to bring about a profound intellectual development. But when the creation of a new mental attitude falls together with extensive material and economic changes, something significant happens. This coincidence of two kinds of change was, I take it, characteristic of the new contacts of the sixteenth and seventeenth centuries. Clash of customs and traditional beliefs dispelled mental inertia and sluggishness; it aroused a lively curiosity as to different and new ideas. The actual adventure of travel and exploration purged the mind of fear of the strange and unknown: as new territories geographically and commercially speaking were opened up, the mind was opened up. New contacts promoted the desire for still more contacts; the appetite for novelty and discovery grew by what it fed upon. Conservative adherence to old beliefs and methods underwent a steady attrition with every new voyage into new parts and every new report of foreign ways. The mind became used to exploration and discovery. It found a delight and interest in the revelations of the novel and the unusual which it no longer took in what was old and customary. Moreover, the very act of exploration, of expedition, the process of enterprising adventure into the remote, yielded a peculiar joy and thrill.