That complexus of knowledge and thought, with its resulting modes of action and feeling, which for the want of a better term we are accustomed to call "the spirit of the age," and which binds into a more or less homogeneous whole the life of all European nations, is created by the action of speech and mainly of opinion ossified and rendered permanent, portable, in the shape of literature. Even in the middle ages it was through this agency that the solidarity of European life was attained. Slow as were the physical means of transport and difficult as in the absence of printing was the diffusion of literature, the interchange was enormous. Mainly through the medium of the Latin tongue, held in common by the cultured of all civilized European countries, thought and knowledge travelled from land to land more slowly, but not less surely, than to-day. The ambassador, the student, and the monk in their travels exchanged thoughts with the men of foreign countries through its medium, and the religious meditation poured forth by the monk in his cell in Spain, the romance shaped by the French poet, the chemical discoveries of the Italian professor, once committed to Latin manuscript, were the property of all Europe. In the pocket of the travelling monk or wandering scholar carefully preserved copies crept from land to land; from the learned class the knowledge of their contents filtered down to the wealthy, and from these to the people, till at last in the German cathedrals were sung the hymns of the Spanish monk, the Dutch chemist perfected the experiments of the Italian, and the romance of the Frenchman, translated from Latin into the colloquial tongues, was sung from end to end of Europe, beside peasant-hearths and baronial castles; and whether we study those centuries in Italy or England, in France or Spain, their spirit, though modified in each, is essentially one.