A new type of thinking is essential if mankind is to survive and move toward higher levels.

Albert Einstein (1879-1955) German-American physicist

Letter (1946-05-25), quoted in “Atomic Education Urged by Einstein,” New York Times
    (Source)

This may be the source of some otherwise unsourced Einstein quotes:

• "The significant problems we face cannot be solved at the same level of thinking we were at when we created them"
• "The world we have created today as a result of our thinking thus far has problems which cannot be solved by thinking the way we thought when we created them."
• "The world we have created is a product of our thinking; it cannot be changed without changing our thinking."
• "This problem will not be solved by the same minds that created it."
• "We cannot solve our problems with the same thinking we used when we created them."
• "We can't solve problems by using the same kind of thinking that created them."

The missive was sent by telegram to "several hundred prominent Americans."

Einstein revisited (alt. source) this theme in "The Real Problem Is in the Hearts of Men," New York Times Magazine (1946-06-23): "Many persons have inquired concerning a recent message of mine that 'a new type of thinking is essential if mankind is to survive and move toward higher levels.' [...] Past thinking and methods did not prevent world wars. Future thinking must prevent wars."