TANSTAAFL, yes!
And while we are quoting the man I love dearly,
"If it cant be expressed in figures, it is not science; it is opinion."
"It is better to copulate than never."
"Do not handicap your children by making their lives easy."
"Be wary of strong drink. It can make you shoot at tax collectors--and miss."
"Waking a person unnecessarily should not be considered a capital crime. For a first offense, that is."
"Freedom begins when you tell Mrs. Grundy to go fly a kite."
I love Heinlein more than is healthy
I had to leave out my favorite Heinleins though, my real favorites would get me banned.
Here's one more, non-Heinlein for you,
"Don't sweat the petty things, and don't pet the sweaty things."
-George Carlin