But the horse's flightiness is not stupidity. It is nature's wisdom and helps the horse to survive in his natural open environment. The horse is a timid creature, and his timidity and flightiness are genetically fixed traits which have been modified but not eliminated by generations of domestication. The ass and its hybrid offspring, the mule, are renowned for their comparative lack of flightiness. The instantaneous flight reaction when frightened could be fatal in such an environment.
Fear is contagious to a horse.
This serves as a survival mechanism in wild horse herds. It is the reason that a young horse gets excited when another horse runs by him. In order to cope with any species the basic behavioral mechanism of that species in the wild state must be identified and accepted. Therefore, the less a horse is frightened when working around it, the less refractory will be its behavior. The horse is a powerful but timid creature and, although completely lacking in reasoning power, is highly intelligent from the standpoint of memory, speed of learning and adaptability.