It is true that the grasping of truth is not possible without empirical basis. However, the deeper we penetrate and the more extensive and embracing our theories become the less empirical knowledge is needed to determine those theories.
Albert EinsteinEinstein was once asked how many feet are in a mile. Einstein's reply was "I don't know, why should I fill my brain with facts I can find in two minutes in any standard reference book?
Albert Einstein