Two days after U2 opened their European summer tour, on August 6 at Olympic Stadium in Turin, Italy, the band's singer, Bono, sat in his home near Nice, France and spoke excitedly and gratefully of his life over the previous few months: the moment he felt something go very wrong in his back, while in training for a North American tour; his emergency operation on May 21; the six weeks he spent in a hospital bed; and his entrance on stage in Turin, to the furious-guitar strains of "Return of the Sting Ray Guitar," one of the many new songs U2 have been writing and recording in recent months.