All breathing, existing, living, sentient creatures should not be slain nor treated with violence, nor abused, nor tormented, nor driven away. This is the pure unchangeable law.
Sutrakritanga (Jainism)

Is there any one maxim which ought to be acted upon throughout one's whole life? Surely the maxim of loving kindness is such: Do not unto others what you would not they should do unto you.
Analects (Confucian)

When you doubt, abstain.
Zoroaster (B.C. 628?-551?)

To see what is right, and not do it, is want of courage, or of principle.
Confucius (B.C. 551-479)

I have enforced the law against killing certain animals and many others, but the greatest progress of righteousness among men comes from the exhortation in favour of non-injury to life and abstention from killing living beings.
Asoka's Edicts (Buddhist)

The human race afraid of nothing, rushes on through every crime.
Horace (B.C. 65-8)

Shame may restrain what law does not prohibit.
Seneca (B.C. 3-65 A.D.)

Treat others as thou wouldst be treated. What thou likest not for thyself, dispense not to others.
Sufism - Abdullah Ansari (Islam)

Every man without passion has within him no principle of action, nor motive of act.
Claude Adrien Helvetius (1715-1771)

Certainly one of the highest duties of the citizen is a scrupulous obedience to the laws of the nation. But it is not the highest duty.
Thomas Jefferson (1743-1826)

Animals are considered as property only. To destroy or to abuse them, from malice to the proprietor, or with an intention injurious to his interest in them, is criminal. But the animals themselves are without protection. The law regards them not substantively. They have no RIGHTS!
Lord (Thomas) Erskine (1750-1823)

To have doubted one's own first principles is the mark of a civilized man.
Oliver Wendell Holmes (1809-1894)

It's faith in something and enthusiasm for something that makes life worth living.
Oliver Wendell Holmes (1809-1894)

What is the use of this fuss about morality when the issue only involves a horse? The first and most difficult teaching of civilisation concerns man's behaviour to his inferiors. Make humanity gentle or reasonable toward animals, and strife or injustice between human beings would speedily terminate.
Dr Edward Mayhew (1813-1868)

I say, break the law.
Henry David Thoreau (1817-1862)

If I repent of anything it is likely to be my good behavior.
Henry David Thoreau (1817-1862)

We live in a world which is full of misery and ignorance, and the plain duty of each and all of us is to try to make the little corner he can influence somewhat less miserable and somewhat less ignorant than it was before he entered it.
Thomas Huxley (1825-1895)

The moral duty to be expected in different ages is not a unity of standard, or of acts, but a unity of tendency ... At one time the benevolent affections embrace merely the family, soon the circle expanding includes first a class, then a nation, then a coalition of nations, then all humanity and finally, its influence is felt in the dealings of man with the animal world.
W.E.H.Lecky (1838-1903)

No folly is more costly than the folly of intolerant idealism.
Winston Churchill (1874-1965)

The important thing is not to stop questioning.
Albert Einstein (1879-1955)

No doubt Jack the Ripper excused himself on the grounds that it was human nature.
A.A.Milne (1882-1956)

No man was ever endowed with a right without being at the same time saddled with a responsibility.
Gerald W. Johnson (1890- )

I would remind you that extremism in the defence of liberty is no vice. And let me remind you also that moderation in pursuit of justice is no virtue.
Barry Goldwater (1909- )

The individual is capable of both great compassion and great indifference. He has it within his means to nourish the former and outgrow the latter.
Norman Cousins (1915- )

I submit that an individual who breaks the law that conscience tells him is unjust and willingly accepts the penalty by staying in jail to arouse the conscience of the community over its injustice, is in reality expressing the very highest respect for law.
Martin Luther King Jr. (1929-1968)

Man must get his thoughts, words and actions out of this vast moral jungle.We are not predators. We are, hopefully, more than instinctive killers and selfish brutes. Why take such a dim view of our potentialities and capabilities?
H.Jay Dinsah (1933- )

Moral education, as I understand it, is not about inculcating obedience to law or cultivating self-virtue, it is rather about finding within us an ever-increasing sense of the worth of creation. It is about how we can develop and deepen our intuitive sense of beauty and creativity.
Andrew Linzey (1952- )