Compassion

Until he extends the circle of compassion to all living things, man will not himself find peace.
~ Albert Schweitzer ~

If you have men who will exclude any of god's creatures from the shelter of compassion and pity, you will have men who will deal likewise with their fellow men.
~ St. Francis of Assisi ~

I have no doubt that it is part of the destiny of the human race in its gradual improvement to leave off eating animals.
~ Henry David Thoreau ~

Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so.
~ Douglas Adams, Last Chance to See ~

Those who make peaceful revolution impossible will make violent revolution inevitable.
~ John F. Kennedy ~

Pain is pain, irrespective of the race, sex or species of the victim.
~ William M Kunster ~

* Now, a funny one:

I am not a vegetarian because I love animals; I am a vegetarian because I hate plants.
~ A. Whitney Brown ~