A first edition of the revolutionary text in which Sir Isaac Newton outlined his theories of gravity and motion sold for $321,500 at auction, more than triple what the Christie's auction house had expected.

Newton's 1687 work "The Mathematical Principles of Natural Philosophy" went to an unidentified buyer from Europe on Tuesday night. Written in Latin, the book outlines Newton's theories of the universe - including his belief that all bodies in space and on earth are affected by gravity.Albert Einstein once said the book was "perhaps the greatest intellectual stride that it has ever been granted to any man to make."