Arthur C. Clarke formulated the following three "laws" of prediction:

1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is probably wrong.

2, The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

3. Any sufficiently advanced technology is indistinguishable from magic.

TANSTAAFL

"There ain't no such thing as a free lunch."

— Robert A. Heinlein (The Moon Is a Harsh Mistress)

"When one teaches, two learn."

— Robert A. Heinlein

"Secrecy begets tyranny."

— Robert A. Heinlein (Stranger in a Strange Land)

"A desire not to butt into other people's business is at least eighty percent of all human wisdom."

— Robert A. Heinlein (Stranger in a Strange Land)

"Never tease an old dog; he might have one bite left."

— Robert A. Heinlein (Time Enough for Love)

"But goodness alone is never enough. A hard, cold wisdom is required for goodness to accomplish good. Goodness without wisdom always accomplishes evil."

— Robert A. Heinlein (Stranger in a Strange Land)

"If you've got the truth you can demonstrate it. Talking doesn't prove it."

— Robert A. Heinlein (Stranger in a Strange Land)

"All generalizations are false, including this one."

Mark Twain

"It's not the size of the dog in the fight, it's the size of the fight in the dog."

Mark Twain