These animals, therefore, are never more to be dreaded than when they are themselves afraid, for at such times they become unmanageable, and seem as if they had lost their senses. As the trade in mules is lucrative in Paraguay, it is also dangerous to the merchants, on account of the exceeding timidity of these animals. Ten thousand mules, entirely free and without bridles, are often driven, by a few Spanish guards, in one drove. At the slightest alarm they all take to flight, hurry over the plain, and hide themselves in interminable deserts, whilst no industry in the horsemen, nor swiftness in the horses, is sufficient to bring them back again. Many have been ruined by mules running away and being lost in this manner. I have been acquainted with men, in other respects brave and intrepid, who, warned by the danger of others, resolved never in their lives to ride on a mule. I have known many more, who, scorning the most excellent horses, would never travel on any other animal. Neither is this preference to be condemned, for mules, though fearful and treacherous, possess many good qualities which do not belong to horses. Their pace, especially that of the amblers, is easy and firm, by which means they always tread with safety, whether they have to ascend rocks or to creep over marshy places, though horses are better for crossing deep marshes and rivers, on account of their height. One mule is sufficient in a long and difficult journey which would fatigue four horses. Mules are contented with the readiest and coarsest food, though generally fat and sleek. Many of them surpass the swiftest horses in speed, as I have often observed in the races of the soldiers. They are longer lived than most other beasts. In the town of S. Joachim I had mules more than thirty years old, which would bear a rider, and sometimes contrive to kick him off too. Moreover they are possessed of athletic strength, for they are accustomed to carry almost four hundred weight, in journies of many months, through very rough roads, when laden with the herb of Paraguay. In a word, I am unable to determine whether the virtues or vices of mules preponderate.