A society that is not willing to demand a life of somebody who has taken somebody else’s life is simply immoral.

Out of the crooked timber of humanity, no straight thing was ever made.

With men, the state of nature is not a state of peace, but war.

We can never, even by the strictest examination, get completely behind the secret springs of action.

Enlightenment is man's emergence from his self-imposed immaturity...No thing is required for this enlightenment.. .except freedom; and the freedom in question is the least harmful of all, namely, the freedom to use reason publicly in all matters.

Reason can never prove the existence of God.

...as soon as we examine suicide from the standpoint of religion we immediately see it in its true light. We have been placed in this world under certain conditions and for specific purposes. But a suicide opposes the purpose of his creator; he arrives in the other world as one who has deserted his post; he must be looked upon as a rebel against God. God is our owner; we are his property; his providence works for our good.