Tao te Ching: 55

He who possesses virtue in abundance
May be compared to an infant.
Poisonous inesects will not sting him.
Fierce beasts will not seize him.
Birs of prey will not strike him.
His bones are weak, his sinews tender, but his grasp is firm.
He does not yet know the union of male and female,
But his organ is aroused.
This means that his essence is at its height.
He may cry all day without becoming hoarse,
This means that his (natural) harmony is perfect.
To know harmony means to be in accord with the eternal.
To be in acord with the eternal means to be enlightened.
To force the growth of life means ill omen.
For the mind to employ the vital force without restraint means violence.
After things reach their prime, they begin to grow old,
Which means being contrary to Tao.
Whatever is contrary to Tao will soon perish.

I admit to balking at this a bit when I first read it. My worldly logic tells me that of course predators will attack a helpless infant. This isn't a matter of physical weakness though. Lao Tzu isn't advocating physical weakness but rather the harmony of youth.

The predators are not animals, per se, but the problems of a mortal life. Don't build up your defenses and don't strike out. Act in harmony with your nature and the slings and arrows of outrageous fortune will miss their target or never become incensed at all. Lao Tzu points out that whatever is contrary to Tao will perish, just as he did in Chapter 30. When we fight against our true nature, we invite suffering and discrimination and death.