Technically both works are extremely difficult. The general breadth of effect, the demand for power and for freedom of the arm, and the use of octaves--these as well as the use of the very high and very low registers of the keyboard--all make evident the rather orchestral idea of the pianoforte which Liszt introduced. Liszt, by the way, was one of the first to recognize the greatness of Franck. But, though Franck was at one time a brilliant pianist and was intended by his father to electrify Europe from the concert stage, he was above all else an organist. His pianoforte style is most evidently very closely allied to the organ style. This is particularly noticeable in the treatment of bass parts, which not only suggest the pedals of the organ but are often impossible for the small hand to play. The octaves for the left hand in the Aria, and even more remarkably those in the Chorale, need not only the independent movement which the organ pedals can add in polyphony, but seem to call for the tone color of the low notes on the organ. Frequently, moreover, as in the second section of the Prelude in the ‘Prelude, Aria, and Finale,’ such wide stretches as the music demands of the hands, as well as the general freedom of polyphonic movement, almost require an instrument with two keyboards. On the other hand, there are many effects which are brilliantly pianistic. The flowing figures in the Prelude of the ‘Prelude, Chorale and Fugue’ are purely pianistic. The tremendous octave passages in the Finale need the distinct, percussive sound of the pianoforte. And the upper notes of the Chorale melody, both when it is given alone and when it is combined with the fugue theme, must have a ringing, bell-like quality which only the pianoforte can produce.