The one who possesses solid virtue is like a newborn baby who does not fear the sting of poisonous animals, nor the claws of ferocious beasts, nor the talons of birds of prey.
His bones are weak, his tendons are soft, and yet he grips objects strongly. He does not yet know the union of the two sexes, and yet his sexual organ shows well his virility. It comes from the perfection of its vital essence. He cries all day and his voice is not altered; it comes from the perfection of harmony (of the life force).
Knowing harmony is called being constant. Knowing constancy is called being enlightened. Living to excess is called being condemned. Acting according to one's passion is called being strong. As soon as somebody reaches the peak of his strength, he begins getting old.
The Tao disapproves of becoming strong. Whoever does not follow the teaching of the Tao will perish quickly.