“The great masquerade of evil has played havoc with all our ethical concepts. For evil to appear disguised as light, charity, historical necessity or social justice is quite bewildering to anyone brought up on our traditional ethical concepts, while for the Christian who bases his life on the Bible, it merely confirms the fundamental wickedness of evil. The "reasonable" people's failure is obvious. With the best intentions and a naive lack of realism, they think that with a little reason they can bend back into position the framework that has got out of joint. In their lack of vision they want to do justice to all sides, and so the conflicting forces wear them down with nothing achieved. Disappointed by the world's unreasonableness, they see themselves condemned to ineffectiveness; they step aside in resignation or collapse before the stronger party.
Still more pathetic is the total collapse of moral fanaticism. Fanatics think that their single-minded principles qualify them to do battle with the powers of evil; but like a bull they rush at the red cloak instead of the person who is holding it; they exhaust themselves and are beaten. They get entangled in non-essentials and fall into the trap set by cleverer people.”

Source: Letters and Papers from Prison (1967; 1997), Who Stands Fast?, p. 4.
Context: The great masquerade of evil has played havoc with all our ethical concepts. For evil to appear disguised as light, charity, historical necessity or social justice is quite bewildering to anyone brought up on our traditional ethical concepts, while for the Christian who bases his life on the Bible, it merely confirms the fundamental wickedness of evil. The "reasonable" people's failure is obvious. With the best intentions and a naive lack of realism, they think that with a little reason they can bend back into position the framework that has got out of joint. In their lack of vision they want to do justice to all sides, and so the conflicting forces wear them down with nothing achieved. Disappointed by the world's unreasonableness, they see themselves condemned to ineffectiveness; they step aside in resignation or collapse before the stronger party.
Still more pathetic is the total collapse of moral fanaticism. Fanatics think that their single-minded principles qualify them to do battle with the powers of evil; but like a bull they rush at the red cloak instead of the person who is holding it; they exhaust themselves and are beaten. They get entangled in non-essentials and fall into the trap set by cleverer people.

Kantian Ethics (2008)

Hay un concepto que es el corruptor y el desatinador de los otros. No hablo del mal cuyo limitado imperio es la ética; hablo del infinito.
"Avatars of the Tortoise"
Variant translations:
One concept corrupts and confuses the others. I am not speaking of the Evil whose limited sphere is ethics; I am speaking of the infinite.
There is a concept that is the corruptor and dazzler of others. I'm not talking about the evil whose limited empire is the ethic; I'm talking about infinity.
There is a concept that is the corrupter and destroyer of all others. I speak not of Evil, whose limited empire is that of ethics; I speak of the infinite.
Discussion (1932)

Source: Between Caesar and Jesus (1899), p. 26

The Way of God's Will Chapter 1-4. Practice http://www.unification.org/ucbooks/WofGW/wogw1-04.htm Translated 1980.

Address http://reto.cn/biblioteko/movado/zamenhof/paroladoj/uk2.htm to the Second World Congress of Esperanto, Geneve, Switzerland. 27 August 1906.

Niels Bohr, "Atomic Physics and the Description of Nature" (1934)

Source: The Limits of Evolution, and Other Essays, Illustrating the Metaphysical Theory of Personal Ideaalism (1905), Appendix B: The System in its Ethical Necessity and its Practical Bearings, p.392

Source: The Expanding Circle: Ethics, Evolution, and Moral Progress (1981), Chapter 6, A New Understanding Of Ethics, p. 149