A mathematician wrote it for 'genius' John Forbes Nash
                                
                                
                                    (Newser) -
                                    Like a strong, simple letter of recommendation? Well it helps if the subject is a genius. Mathematician Richard Duffin wrote a letter to Princeton University for John Forbes Nash, Jr., who became an esteemed mathematician and the subject of the film A Beautiful Mind,  Mashable  reports. Dated Feb. 11, 1948,...