As a Famous Moderator once said, “I’m moving this to Cafe Society.”
Tom Lehrer,
“Life is like a sewer, you only get out of it what you put into it.”
“Plagerize, plagerize, plagerize,… only please call it research.”
Robert Heinlein,
“An elephant is mouse built to goverment specifications.”
“Ever notice how they look like orchids?” 
Since you like Mencken, check out The Devil’s Dictionary, the masterwork of the cynical Ambrose Bierce.
Bertrand Russel: “Supposing you got a crate of oranges that you opened, and you found all the top layer of oranges bad, you would not argue, ‘The underneath ones must be good, so as to redress the balance’; You would say, ‘Probably the whole lot is a bad consignment’; and that is really what a scientific person would say about the universe.”
And TP, obviously, but everyone knows everything he’s said by now 
Seconded: Wilde, Dorothy Parker, H.L. Mencken.
I came across this great quote in one of George Orwell’s essays: “One has to belong to the intelligentsia to believe things like that: no ordinary man could be such a fool.”
All these postings and not 1 vote for the great American philosopher
Yogi Berra ???
“If you don’t know where you’re going, you’re never going to get there.”
In a more serious vein, Teddy Roosevelt had many profound quotes:
“Far better it is to dare mighty things, to win glorious triumphs, even though checkered by failure, than to take rank with those poor spirits who neither enjoy much nor suffer much, because they live in the gray twilight that knows not victory nor defeat.”
A Google search will reveal many more.
A little known French writer named Hugues de Montalembert.
“I detest waiting, monotony and routine
and yet it is with those very ingredients
that empires have been built.”
You know what “annoys the hell out of me”? People who seems to think Hepburn’s “good acting” suddenly began with The Philadelphia Story, or the Tracy films.
Forgetting, of course, films like Little Women, Stage Door, Bringing Up Baby, Holiday, not to mention her numerous turns on stage (including Philadelphia in 1939).
And please…“breezed into town with perfect bone structure and her family’s money”?
If only it were that easy. :rolleyes:
In a darker vein (hey nothing in the OP said they have to be thought provoking quotes) hands down no argument Clive Barker.
“Oh no tears Kirsty such a waste of suffering”
“The remains of a very disappointing victim…but we’re hoping you’ll make up for it”
“There is a sound in the center of the earth…it’s RAZORS THROUGH FLESH. I am merely here to turn up the volume.”
“I was born to murder the world”
“You came to me as sheep…but I am not a Shepard”
Even as much as his movies consistently suck there’s always a good line or two I take from them.
I always liked Archie Goodwin quotes in Rex Stout’s Nero Wolfe mysteries. The one that always stuck with me was Archie describing a woman with “lipstick an inch thick.”
Leander, hello A Hepburn fan.
Eve, I tend to agree with your judgement of her acting quotes, and I prefer her quotes about life in general.
But I absolutely adore Bringing up Baby. And Philadelphia Story. Those are the movies that made me love Kate.
Thera, hello to you, as well.
I probably shouldn’t have been so pissy. I just hate it when people dismiss her early career and swoon over the later stuff. She gave some wonderful performances early on, and it’s worth taking a look at them if you are a fan of hers…or just interested in seeing some damn fine films.
PJ O’Rourke, though I seldom agree with him, is eminently quotable. Michael O’Donoghue, too.
Villains are better quote sources than heroes. I’m hard-pressed to think of anything by Eisenhower or Audie Murphy as good as this gem by Herrmann Goerring: “When people speak of ‘culture,’ I reach for my Browning.”
Take care of the cojones and the frijoles will take care of themselves.
–Robert Heinlein
If it can be conceived as music, it can be executed as music, and presented to an audience in such a way that they will perceive it as music: “Look at this. Ever seen one of these before? I built this for you. What do you mean, ‘What the fuck is it?’ It’s a goddam ETUDE, asshole.”
–Frank Zappa
I am writing a manifesto and there’s nothing I want, and yet I’m saying certain things, and in principle I am against manifestos, as I am against principles (quantifying measures of the moral value of every phrase — too easy; approximation was invented by the impressionists). I’m writing this manifesto to show that you can perform contrary actions at the same time, in one single, fresh breath; I am against action; as for continual contradiction, and affirmation too, I am neither for nor against them, and I won’t explain myself because I hate common sense.
– Tristan Tzara
God is a comedian playing to an audience too afraid to laugh.
– Voltaire
I do have a cause, though. It is obscenity. I’m for it.
– Tom Lehrer
Yeah, he’s da man.
Another vote for the noted zen philosopher Peter Lawrence Berra.
One of my other favorites is Robert Benchley:
“A great many people have come up to me and asked how I manage to get so much work done and still keep looking so dissipated.”
“Anyone can do any amount of work provided it isn’t the work he is supposed to be doing at the moment.”
“It took me fifteen years to discover that I had no talent for writing, but I couldn’t give it up because by that time I was too famous.”
“Great literature must spring from an upheaval in the author’s soul. If that upheaval is not present then it must come from the works of any other author which happens to be handy and easily adapted.”
Damn. Lawence Peter, that is.