A collection of my favourite quotes. Some people think that the use of quotes shows a lack of originality; personally, I would rather take advantage of someone else's hard work in condensing a good idea down to as few, memorable words as possible.
"Smart people believe weird things because they are skilled at defending beliefs they arrived at for non-smart reasons." - Michael Shermer
"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
"That which can be asserted without evidence, can be dismissed without evidence."- Christopher Hitchens. Very useful to keep in mind if you ever face unreasonable journal reviewers.
"Never memorize what you can look up in books." - Albert Einstein.
"Hindsight is not only clearer than perception-in-the-moment but also unfair to those who actually lived through the moment." - Edwin S. Shneidman
"He who increases not [his knowledge], decreases" - Hillel the elder.
"The man who doesn't read good books has no advantage over the man who can't" - Mark Twain
"A false ideology will typically tempt us to frame the wrong questions and thereby waste time and effort on low-grade research and avoidable artifactual puzzles. But sometimes one can make progress even while asking awkward and misguided questions, and sometimes (quite often, in fact, I think), researchers half-consciously know better than to actually ask the questions their ideology holds to be the right questions. Instead they ask questions they can see how to answer and hardly notice that these inquiries are rather remotely related to the official questions of their school of thought." - Daniel C Dennett (Brainchildren, p220).
"When an elderly but distinguished scientist says that something is possible, he is almost certainly right; but if he says that it is impossible, he is very probably wrong." - Arthur C Clarke
"It does not matter who you are, or how smart you are, or what title you have, or how many of you there are, and certainly not how many papers your side has published, if your prediction is wrong then your hypothesis is wrong. Period." - Richard Feynman
"There are a thousand hacking at the branches of evil to one who is striking at the root." - Henry David Thoreau
"It is not enough to be industrious; so are the ants. What are you industrious about?" - Henry David Thoreau
"Simple statements are to be prized more highly than less simple ones because they tell us more; because their empirical content is greater; and because they are better testable." - Karl Popper
"The business schools reward difficult complex behavior more than simple behavior, but simple behavior is more effective." - Warren Buffett. [I'd say that quote applies to all of academia, at least, when it comes to publishing journal articles...]
Finance & politics
"Annual income twenty pounds, annual expenditure nineteen pounds nineteen and six, result happiness. Annual income twenty pounds, annual expenditure twenty pounds, nought and six, result misery." - Micawber, (Charles Dickens).
"Economists are those who when seeing something working in practice wonder whether it really works in theory."
"All political thinking for years past has been vitiated in the same way. People can foresee the future only when it coincides with their own wishes, and the most grossly obvious facts can be ignored when they are unwelcome.” - George Orwell
"Anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your knowledge." - Isaac Asimov
"Men, it has been well said, think in herds; it will be seen that they go mad in herds, while they only recover their senses slowly, and one by one." - Charles Mackay [ should I file this one under 'Academia'...? ;) ]
"Any fool can make a rule ; And any fool will mind it." - Henry David Thoreau
"Not everything that counts can be counted, and not everything that can be counted counts." - WB Cameron.
"A little knowledge that acts is worth infinitely more than much knowledge that is idle." - K. Gibran
"Strange is our situation here upon earth. Each of us comes for a short visit, not knowing why, yet sometimes seeming to a divine purpose. From the standpoint of daily life, however, there is one thing we do know: That we are here for the sake of others...for the countless unknown souls with whose fate we are connected by a bond of sympathy. Many times a day, I realize how much my outer and inner life is built upon the labors of people, both living and dead, and how earnestly I must exert myself in order to give in return as much as I have received." - A. Einstein.
"Remembering that I'll be dead soon is the most important tool I've ever encountered to help me make the big choices in life. Because almost everything — all external expectations, all pride, all fear of embarrassment or failure - these things just fall away in the face of death, leaving only what is truly important. Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart." - Steve Jobs
"Those who do not move do not notice their chains." - Rosa Luxemburg
"People will always despise you if you end up doing less stupid BS than they choose to suffer.” - Merlin Mann
"If not now, when?" - Hillel the Elder. I was recently amazed to discover this quote is over 2000 years old!
If you liked these, you might enjoy the LessWrong.com monthly 'rationality quote' discussion: Less Wrong
There's also an amazing repository of interesting quotes at Wikiquote, that most people are unaware of...