Clarke's Three Laws
1 - When a distinguished but elderly scientist states that something is possible, he is almost certainly right.
When he states that something is impossible, he is very probably wrong.
-- Arthur C. Clarke. "Hazards of Prophecy: The Failure of Imagination". Profiles of the Future. 1962
restated in: "Technology and the Future". Report on Planet Three. 1972

Asimov's Corollary to Clarke's First Law
When, however, the lay public rallies round an idea that is denounced by distinguished but elderly scientists and supports that idea with great fervor and emotion -- the distinguished but elderly scientists are then, after all, probably right.
-- Isaac Asimov. F&SF. Feb 1977

2 - The only way to discover the limits of the possible is to go beyond them into the impossible.
-- Arthur C. Clarke. "Technology and the Future". Report on Planet Three. 1972

3 - Any sufficiently advanced technology is indistinguishable from magic.
-- Arthur C. Clarke. "Technology and the Future". Report on Planet Three. 1972

Benford's Corollary to Clarke's Third Law:
Any technology distinguishable from magic is insufficiently advanced.
-- Gregory Benford. Foundation's Fear. 1997

Any sufficiently advanced bug is indistinguishable from a feature.
-- Rich Kulawiec

Clarke's Law of Revolutionary New Ideas on space exploration
Like all revolutionary new ideas, the subject has had to pass through three stages, which may be summed up by these reactions: (1) 'It's crazy --- don't waste my time.' (2) 'It's possible, but it's not worth doing.' (3) 'I always said it was a good idea.'
-- Arthur C. Clarke. "Next---The Planets!" Report on Planet Three. 1972

compare
First, you know, a new theory is attacked as absurd; then it is admitted to be true, but obvious and insignificant; finally it is seen to be so important that its adversaries claim that they themselves discovered it.
-- William James, Pragmatism, lecture 6, 1907

Haldane's Law
The universe is not only queerer than we imagine; it is queerer than we can imagine.
-- J. B. S. Haldane. 1892--1964

Hofstadter's Law
It always takes longer than you expect, even when you take into account Hofstadter's Law.
-- Douglas Hofstadter, Gödel, Escher, Bach, chapter 5, 1979

Meyer's Seven Sins of the Specifier
Noise
The presence in the text of an element that does not carry information relevant to any feature of the problem. Variants: redundancy; remorse.
Silence
The existence of a feature of the problem that is not covered by any element of the text.
Overspecification
The presence in the text of an element that corresponds not to a feature of the problem but to features of a possible solution.
Contradiction
The presence in the text of two or more elements that define a feature of the system in an incompatible way.
Ambiguity
The presence in the text of an element that makes it possible to interpret a feature of the problem in at least two different ways.
Forward reference
The presence in the text of an element that uses features of the problem not defined until later in the text.
Wishful thinking
The presence in the text of an element that defines a feature of the problem in such a way that a candidate solution cannot realistically be validated with respect to this feature.
-- Bertrand Meyer, IEEE Software, Jan 1985

Occam's Razor
Entia non sunt multiplicanda praeter necessitatem
Entities ought not to be multiplied except from necessity... or ... Keep it as simple as possible
-- William of Ockham. 1280?--1349

Sturgeon's Law
Ninety percent of everything is crud
-- Ted Sturgeon, World Science Fiction Covention, Philadelphia, 1953

as related in the anecdote
"When people talk about the mystery novel," Ted said, as I remember, "they mention The Maltese Falcon and The Big Sleep. When they talk about the western, they say there's The Way West and Shane. But when they talk about science fiction, they call it 'that Buck Rogers stuff,' and they say 'ninety percent of science fiction is crud.' Well, they're right. Ninety percent of science fiction is crud. But then ninety percent of everything is crud, and it's the ten percent that isn't crud that is important. And the ten percent of science fiction that isn't crud is as good as or better than anything being written anywhere."
-- James Gunn, The New York Review of Science Fiction #85, September 1995

Corollary to Sturgeon's Law
The Golden Age looks so good because we've forgotten the 90% that's crap.
-- Lee Ann Rucker, rec.arts.sf.written, Jan 2001

Michael Gelb's Seven Da Vincian Principles
Curiosità
An insatiably curious approach to life and an unrelenting quest for continuous learning.
Dimostrazione
A commitment to test knowledge through experience, persistence, and a willingness to learn from mistakes.
Sensazione
The continual refinement of the senses, especially sight, as means to enliven experience.
Sfumato (literally "Going up in Smoke")
A willingness to embrace ambiguity, paradox, and uncertainty.
Arte/Scienza
The development of the balance between science and art, logic and imagination. "Whole-brain" thinking.
Corporalita
The cultivation of grace, ambidexterity, fitness, and poise.
Connessione
A recognition of and appreciation for the interconnectedness of all things and phenomena. Systems thinking.

Assorted quotations
You can pretend to be serious; you can't pretend to be witty
-- Sacha Guitry

Curiositas, Patientia, Formositas