Reason, observation, and experience; the holy trinity of science.
I would rather live and love where death is king than have eternal life where love is not.
I will not attack your doctrines nor your creeds if they accord liberty to me. If they hold thought to be dangerous - if they aver that doubt is a crime, then I attack them one and all, because they enslave the minds of men.
There can be but little liberty on earth while men worship a tyrant in heaven.
Hope is the only universal liar who never loses his reputation for veracity.
Surely there is grandeur in knowing that in the realm of thought, at least, you are without a chain; that you have the right to explore all heights and depth; that there are no walls nor fences, nor prohibited places, nor sacred corners in all the vast expanse of thought.
Happiness is the only good. The time to be happy is now. The place to be happy is here. The way to be happy is to make others so.
Happiness is not a reward - it is a consequence. Suffering is not a punishment - it is a result.
Give to every human being every right that you claim for yourself.
A fact never went into partnership with a miracle. Truth scorns the assistance of wonders. A fact will fit every other fact in the universe, and that is how you can tell whether it is or is not a fact. A lie will not fit anything except another lie.
If a man would follow, today, the teachings of the Old Testament, he would be a criminal. If he would follow strictly the teachings of the New, he would be insane.
Anger is a wind which blows out the lamp of the mind.
I am the inferior of any man whose rights I trample under foot.
Courage without conscience is a wild beast.
Every man is dishonest who lives upon the labor of others, no matter if he occupies a throne.