"If such a demand is made, we would best meet it by all wearing the Star of David." -King Christian X of Denmark (Personal diary entry of September 10, 1941, reporting on a meeting with one of his ministers, discussing the possibility that the Nazi occupiers might demand that Danish Jews wear the yellow Star of David.)
"Symmetry is ennui, and ennui is the very essence of grief and melancholy." -Victor Hugo (Les Miserables).
"That grown men and women can make a living pondering such matters is a sign that civilization, as fragile as it may sometimes seem,
remains intact." -George Johnson (The New York Times, April 20,
2003). This was an early article on Perelman's work.
"The object of mathematical rigour is to sanction and legitimize the conquests of intuition, and there was never any other object for it." -Jacques Hadamard.
"Do not be bitter, deceptive or petty." -A fortune cookie I received twice during graduate school.
This is excellent advice, which I try to follow, but apparently the fortune cookie people were worried about me.
"Incredible claims require incredible evidence."-Dennis Overbye (in "Tiny Neutrinos May Have Broken Cosmic Speed Limit," The New York Times, September 22, 2011.) The second occurrence of "incredible" in the sentence is unfortunate.
"This paper has been withdrawn because the authors have failed to come to a final verdict on who is the main contributor to this paper and who should be its owner as well as who should be on the author list and who shouldn't."-From an abstract on the arXiv that, perhaps, it's kinder not to identify further.
This may be the best line I've ever seen in an abstract.