C. Julius Caesar, Gallic War

Merchants have access to them rather that they may have persons to whom they may sell those things which they have taken in war, than because they need any commodity to be imported to them. Moreover, even as to laboring cattle, in which the Gauls take the greatest pleasure, and which they procure at a great price, the Germans do not employ such as are imported, but those poor and ill-shaped animals, which belong to their country; these, however, they render capable of the greatest labor by daily exercise. In cavalry actions they frequently leap from their horses and fight on foot; and train their horses to stand still in the very spot on which they leave them, to which they retreat with great activity when there is occasion; nor, according to their practice, is any thing regarded as more unseemly, or more unmanly, than to use housings. Accordingly, they have the courage, though they be themselves but few, to advance against any number whatever of horse mounted with housings. They on no account permit wine to be imported to them, because they consider that men degenerate in their powers of enduring fatigue, and are rendered effeminate by that commodity.