“It is the enemy who can truly teach us to practice the virtues of compassion and tolerance.”

Source: I Thought It Was Just Me: Women Reclaiming Power and Courage in a Culture of Shame

Liebt man sich wirklich, so ist es ja nicht schwer, die Toleranz zu üben, denn die Toleranz ist die Tochter der Liebe -- es ist die eigentlich christliche Eigenschaft, die freilich von der heutigen Christenwelt nicht geübt wird.
in a letter to his father dated 7 April 1851, published in Briefe an seite Eltern, 1839 bis 1864 (1907).

The Better Part (1901)
Context: No man who believes in force and violence is an Anarchist. The true Anarchist decries all influences save those of love and reason. Ideas are his only arms.
Being an Anarchist I am also a Socialist. Socialism is the antithesis of Anarchy. One is the North Pole of Truth, the other the South. The Socialist believes in working for the good of all, while Anarchy is pure Individualism. I believe in every man working for the good of self; and in working for the good of self, he works for the good of all. To think, to see, to feel, to know; to deal justly; to bear all patiently; to act quietly; to speak cheerfully; to moderate one's voice — these things will bring you the highest good. They will bring you the love of the best, and the esteem of that Sacred Few, whose good opinion alone is worth cultivating. And further than this, it is the best way you can serve Society — live your life. The wise way to benefit humanity is to attend to your own affairs, and thus give other people an opportunity to look after theirs.
If there is any better way to teach virtue than by practicing it, I do not know it.
Would you make men better — set them an example. The millenium will never come until governments cease from governing, and the meddler is at rest. Politicians are men who volunteer the task of governing us, for a consideration. The political boss is intent on living off your labor. A man may seek an office in order to do away with the rascal who now occupies it, but for the most part office-seekers are rank rogues. Shakespeare used the word politician five times, and each time it is synonymous with knave. That is to say, a politician is one who sacrifices truth and honor for policy. The highest motive of his life is expediency — policy. In King Lear it is the "scurvy politician," who through tattered clothes beholds small vices, while robes and furred gowns, for him, covers all.

22 August 1875.
The Walk With God (1919)

Verse 251.
Tirukkural

Source: American Fascists: The Christian Right and the War on America, Chapter One: Faith, p. 11

Source: Ashtanga Yoga Primer, 1981, p.58

Maurice in “Characters,” p. 298
Pretexts: Reflections on Literature and Morality (1964)
Context: In my present insistence on high standards you will see that there is less self-indulgence than resolve and application. I do not let the Christian monopolize the ideal of perfection. I have my own virtue, which I am constantly cultivating and refining by teaching myself not to tolerate in me or my surroundings anything but the exquisite.

NOW interview (2002)
Context: Compassion is not a popular virtue. Very often when I talk to religious people, and mention how important it is that compassion is the key, that it's the sine qua non of religion, people look kind of balked, and stubborn sometimes, as much to say, "what's the point of having religion if you can't disapprove of other people?" And sometimes we use religion just to back up these unworthy hatreds, because we're frightened too.