“The oldest, shortest words— "yes" and "no"— are those which require the most thought.”

Source: Outwitting the Devil: The Secret to Freedom and Success

Volume II, chapter V, section 30.
Source: The Stones of Venice (1853)

Source: The Black Album

What Would You Substitute for the Bible as a Moral Guide? (1900)
Context: What then is, or can be called, a moral guide? The shortest possible answer is one word: Intelligence. We want the experience of mankind, the true history of the race. We want the history of intellectual development, of the growth of the ethical, of the idea of justice, of conscience, of charity, of self-denial. We want to know the paths and roads that have been traveled by the human mind. These facts in general, these histories in outline, the results reached, the conclusions formed, the principles evolved, taken together, would form the best conceivable moral guide. We cannot depend on what are called “inspired books,” or the religions of the world. These religions are based on the supernatural, and according to them we are under obligation to worship and obey some supernatural being, or beings. All these religions are inconsistent with intellectual liberty. They are the enemies of thought, of investigation, of mental honesty. They destroy the manliness of man. They promise eternal rewards for belief, for credulity, for what they call faith. This is not only absurd, but it is immoral.

Source: The Buddha of Suburbia

Opera and Drama (1851)

Source: Islands in the Net (1988), Chapter 11 (p. 389)

Made to Last (1964), ch. 4