Orfeo ed Euridice was first given at the Burgtheater in Vienna on 5 October 1762, for the name day of Emperor Francis I, with the castrato Gaetano Guadagni in the title role. Gluck and his librettist Ranieri de' Calzabigi cut away the apparatus of opera seria — the exit arias, the coloratura written for singers rather than characters, the tangle of subplots — and left three principals, a chorus and one continuous action. Gluck rewrote the work for Paris in 1774, transposing Orphée for a high tenor. The reform announced here reshaped serious opera for a century.