I am often inspired by the phrases of remarkable thinkers. Whether serious or just plain funny, several of them carry important insights about our human condition and offer valuable ideas that help us understand our own nature. Here are some I appreciate:

"The greatest enemy of truth is very often not the lie -- deliberate, contrived, and dishonest -- but the myth -- persistent, pervasive, and unrealistic"
John F. Kennedy

"You can't change anything by fighting or resisting it. You change something by making it obsolete through superior methods"
Buckminster Fuller

"In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual"
Galileo Galilei

"It has been said that the primary function of schools is to impart enough facts to make children stop asking questions. Some, with whom the schools do not succeed, become scientists..."
Knut Schmidt-Nielsen

"Understanding is more often used to try to alter an outcome than to repeat or perpetuate it"
Jared Diamond, in Guns, Germs and Steel

"AI is an engineering discipline build on an unfinished science"
Matthew Ginsberg, in SIGART Bulletin Vol 6, No. 2, April 1995

"If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization"
Gerald Weinberg

"Fundamental progress cannot be achieved through incremental advances in existing technology"
John McCarthy, cited in Essentials of Artificial Intelligence, by Matt Ginsberg

"Dreams are maps"
Carl Sagan

"The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time and still retain the ability to function"
F. Scott Fitzgerald, The Crack-Up

"Desires provides the ends, thinking provides the means"
Robert Sokolowski, in Natural and Artificial Intelligence

"...the only meaning of life worth caring about is the one that can withstand our best efforts to examine it"
Daniel C. Dennett, Darwin's Dangerous Idea

"Every time I see an adult on a bicycle, I no longer despair for the future of the human race"
H. G. Wells

"Life is a sexually transmitted disease"

"I would never die for my beliefs because I might be wrong"
Bertrand Russell (suicidal terrorists should think seriously about this)

"Ask an impertinent question and you're on the way to a pertinent answer"
Jacob Bronowski

"By all means let's be open-minded, but not so open-minded that our brains drop out"
Richard Dawkins

"The goal of science is to build better mousetraps. The goal of nature is to build better mice"

"Actually, Occam wore a beard: philosophers kept borrowing his razor"

"New scientific truth usually becomes accepted, not because opponents become convinced, but because opponents die, and because the rising generation is familiar with the new truth at the outset"
Max Planck

"It is not what the man of science believes that distinguishes him, but how and why he believes it"
Bertrand Russell

"I am returning this otherwise good typing paper to you because someone has printed gibberish all over it and put your name at the top"
an English Professor at Ohio University

"I wish to propose for the reader's favourable consideration a doctrine which may, I fear, appear wildly paradoxical and subversive. The docrine in question is this: that it is undesirable to believe a proposition when there is no ground whatever for supposing it true"
Bertrand Russell

"I don't think so. . .      "
René Descartes, just before dying (it's a joke!)

"Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so"
Douglas Adams, Last Chance to See

"Consider the ignorance of the average fundamentalist. Then realize that by definition fully half of them must be even more ignorant than that."

"Those who cavalierly reject the Theory of Evolution, as not adequately supported by facts, seem quite to forget that their own theory is supported by no facts at all."
Herbert Spencer (1820-1903)

"Philosophy of science is about as useful to scientists as ornithology is to birds"
Richard Feynman

"Attempting to make fun of pseudoscience is a difficult task, for one must compete with pseudoscientists producing funnier material while being absolutely serious"
Donald E. Simanek

"Belief in the absence of compelling evidence is called faith. Belief after acquiring compelling evidence is called knowledge"
Carl Sagan

"I have made a ceaseless effort not to ridicule, not to bewail, not to scorn human actions, but to understand them"
Baruch Spinoza

"Computer Science is no more about computers than astronomy is about telescopes"
E. W. Dijkstra

"Don’t listen to authorities. Find out what the problem is, get the facts, and make up your own mind. Use the scientific method to work things out."
Endel Tulving

"The difference between intelligence and stupidity is that intelligence is bounded"
Roberto Campos, former brazilian politician 

"Perpetual machines are driven by ignorance of Physics"
Sergio Navega (my humble contribution to this list) 

"The task is, not so much to see what no one has yet seen; but to think what nobody has yet thought, about that which everybody sees"
Erwin Schrödinger 

"Every man depends on the work of his predecessors. When you hear of a sudden unexpected discovery -- a bolt from the blue as it were -- you can always be sure that it has grown up by the influence of one man on the other, and it is this mutual influence which makes the enormous possibility of scientific advance"
Lord Rutheford 

"The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt"
Bertrand Russell 

"Intolerance is the natural concomitant of strong faith; tolerance grows only when faith loses certainty; certainty is murderous"
Will Durant, Philosopher 

"I can't understand why people are frightened of new ideas. I'm frightened of the old ones"
John Cage, american composer 

"Those who make peaceful revolution impossible will make violent revolution inevitable"
John F. Kennedy 

Want to suggest another one? Send it to me

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Transparencies from seminars (mostly in Portuguese)
Selected Newsgroup Messages
Line of Seminars (in Portuguese)