Similar quotesIf 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.
George Bernard Shaw 
The difficulty lies not in the new ideas but in escaping the old ones which ramify for those brought up as most of us have been into every corner of our minds.
John Maynard Keynes 
A good idea, only be sure to make a copy of everything before getting rid of it.
Samuel Goldwyn 
An invasion of armies can be resisted, but not an idea whose time has come.
Victor Hugo 
Of all the things I've lost, I miss my mind the most.
Mark Twain 