Horses have hoofs to carry them over frost and snow; hair, to protect them from wind and cold. They eat grass and drink water, and fling up their heels.... Such is the real nature of horses.
ZhuangziSorrow and happiness are the heresies of virtue; joy and anger lead astray from TAO; love and hate cause loss of virtue. The heart unconscious of sorrow and happiness - that is perfect virtue. One, without change - that is perfect repose. Without any obstruction - that is the perfection of the unconditioned. Holding no relations with the external world, - that is perfection of the negative state. Without blemish of any kind, - that is the perfection of purity.
Zhuangzi