Talking with a Martian is like talking with an echo. You don't get argument but you don't get results.

Heinlein's Rules for Writers Rule One: You Must Write Rule Two: Finish What Your Start Rule Three: You Must Refrain From Rewriting, Except to Editorial Order Rule Four: You Must Put Your Story on the Market Rule Five: You Must Keep it on the Market until it has Sold

I believe that this hairless embryo with the aching, oversize brain case and the opposable thumb, this animal barely up from the apes, will endure --will endure longer than his home planet, will spread out to the other planets, to the stars, and beyond, carrying with him his honesty, his insatiable curiosity, his unlimited courage --and his noble essential decency. This I believe with all my heart.

Death isn't funny." "Then why are there so many jokes about death? Jill, with us — us humans — death is so sad that we must laugh at it.

The lessons of history teach us - if the lessons of history teach us anything - that nobody learns the lessons that history teaches us.

A community where everyone is a ruthless murderer, with handy access to death-dealing devices, is a very polite community.

Progress isn't made by early risers. It's made by lazy men trying to find easier ways to do something.