Laudator Temporis Acti

Many of the sayings attributed to Gustave Flaubert in Julian Barnes' Flaubert's Parrot (New York: Knopf, 1985) actually come from Flaubert's works or letters. But I haven't been able to find the source of this, despite its Flaubertian ring:

Let us have the modesty of wounded animals, who withdraw into a corner and remain silent. The world is full of people who bellow against providence. One must, if only on the score of good manners, avoid behaving like them.

Walt Whitman, Song of Myself 32:

I think I could turn and live with animals, they are so placid and self-contain'd,
I stand and look at them long and long.

They do not sweat and whine about their condition,
They do not lie awake in the dark and weep for their sins,
They do not make me sick discussing their duty to God,
Not one is dissatisfied, not one is demented with the mania of owning things,
Not one kneels to another, nor to his kind that lived thousands of years ago,
Not one is respectable or unhappy over the whole earth.

D.H. Lawrence, Self-Pity:

I never saw a wild thing
sorry for itself.
A small bird will drop frozen dead from a bough
without ever having felt sorry for itself.