“Einstein’s great friend and intellectual sparring partner Niels Bohr had a nuanced view of truth. Whereas according to Bohr, the opposite of a simple truth is a falsehood, the opposite of a deep truth is another deep truth. In that spirit, let us introduce the concept of a deep falsehood, whose opposite is likewise a deep falsehood. It seems fitting to conclude this essay with an epigram that, paired with the one we started with, gives a nice example: “Naïveté is doing the same thing over and over, and always expecting the same result.””

Essay on Freud (16 May 1929)

The Deliverance from Error https://www.amazon.com/Al-Ghazalis-Path-Sufism-Deliverance-al-Munqidh/dp/1887752307

Letter to Robert Wilberforce (Rome, 15 February 1848); in Edmund Sheridan Purcell, Life of Cardinal Manning, Vol. I (London: Macmillan and Co., 1896), p. 513.

Source: Personal Destinies: A Philosophy of Ethical Individualism (1976), p. 9

They resemble the ocean itself; always there — vast, fathomless, sublime, the same in its majesty, its inexhaustible fullness, yesterday, to-day, and forever; the same in calm and storm, by day and by night; changeless while generations come and pass; everlasting while ages are rolling away.
Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 261.

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 17 : The Marriage of Skepticism and Wonder
Context: At the heart of science is an essential balance between two seemingly contradictory attitudes - an openness to new ideas, no matter how bizarre or counterintuitive, and the most ruthlessly skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense. The collective enterprise of creative thinking and skeptical thinking, working together, keeps the field on track. Those two seemingly contradictory attitudes are, though, in some tension.

Satyre III (c. 1598)

Source: Brave New World Revisited (1958), Chapter 11 (p. 104)