The strength of a man may be still further estimated by agility and the continuance of his labour. Men accustomed to running outstrip horses, or at least continue their speed for a greater length of time. A man will walk down a horse if they continue together, and perform a long journey much sooner, and with less fatigue. The royal messengers of Ispahan, who are runners by profession, go 36 leagues in 14 or 15 hours. Travellers assure us, that the Hottentots out-run lions in the chace, and that the savages, who live by hunting, pursue the elk and other animals with such speed as to take them. Many other surprising things are told of the nimbleness of savages, and of the long journeys they accomplish on foot, over the most craggy mountains, and the most unfavourable roads, where there is no path to direct, and every obstacle to oppose. A thousand leagues are these people said to travel in less than six weeks, or two months. Birds excepted, whose muscles are indeed stronger in proportion than those of any other animal, no other creature could support such a continuance of fatigue. The civilized man is ignorant of his own strength; nor is he sensible how much he loses of it by effeminacy, and how he might add to it by the habit of vigorous exercise. Sometimes we find men of extraordinary strength; but this gift of Nature, which would be valuable to them in a primitive state, is of very trifling service with the polished part of mankind, among whom mental perfections are held in higher estimation than bodily, and manual exertions are confined to persons of the lowest classes.