TANSTAAFL!

"There Ain't No Such Thing As A Free Lunch" is a phrase that science fiction fans commonly encounter in Robert Heinlein's novel, "The Moon Is A Harsh Mistress." The phrase did not originate with Heinlein, although he makes good use of it. It goes back at least to 1949 and possibly to 1938. I didn't make a careful search of the usage, but from my perspective the phrase means something rather fundamental in economics. I'd phrase it as: "Everything has a cost!" If you think you're getting something for free, then someone else is paying for it and you might want to know what they are getting for the privilege of giving you something "free." Usually you're paying much more than the cost or there would be no benefit to your benefactor. This may sound a little cynical, and there are people who truly provide free lunches and store up treasure in heaven, but I'm not generally talking about them. TANSTAAFL fits in with the related notion that "If it sounds too good to be true, then it isn't."