... or rather incomplete. This quote is often used as a good rationale for sharing ideas, and as a nub of an idea it's good, but incomplete:

If you have an apple and I have an apple and we exchange apples then you and I will still each have one apple. But if you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas.

It's nice and on a most basic of levels it's true. However it's utterly incomplete as anyone who's worked on anything based on sharing ideas, be it brainstorming, collaborative working, open source or anything else. It's actually more a combinatorial explosion of ideas you get and in fact with just two "completely atomic" ideas you never have just 2 ideas, you always have at least 3 - A, B, meld(AB). In fact this sequence should bring flashbacks to many people to their maths:

The reason it's wrong is because of this:

• 2 ideas A, B -> A, B, meld(AB)
• 3 possibilities
  
  
• 3 ideas A, B, C -> A, B, C, meld(AB), meld(BC), meld(AC), meld(ABC)
• 7 possibilities
  
  
• 4 ideas A, B, C -> A, B, C, D, meld(AB), meld(AC), meld(AD), meld(BC), meld(BD), meld(CD), meld(ABC), meld(ABD), meld(ACD),meld(BCD), meld(ABCD)
  
• 15 possibilities
  
  
• More generally: 2**N -1 possibilities
  

Becomes more true when you realise most ideas aren't atomic ideas. OK, not all combinations are valid and useful, but very rarely does sharing 2 ideas leave both parties with just 2 ideas... :-)