Of the means by which Bach attained to such an altitude as a composer for the Organ we may notice his harmonic treatment of the old Church modes, his use of the obbligato pedal, and his original registration. The remoteness of the ecclesiastical modes from our twenty-four major and minor keys renders them particularly appropriate to the service of religion. Any one who looks at Bach’s simple four-part Hymn tunes (Choralgesänge) will at once convince himself of the fact. But no one can realise how the Organ sounds under a similar system of harmonic treatment unless he has heard it. It becomes a choir of four or five parts, each in its natural compass. Compare the following chords in divided harmony: [Divided Harmony, Bach treatment] with these: [Divided Harmony, conventional treatment] which is the more usual form organists employ. We realise instantly the effect when music in four or more parts is played in the same manner. Bach always played the Organ so, adding the obbligato pedal, which few organists know how to use properly. He employed it not only to sound the low notes which organists usually play with the left hand, but he gave it a regular part of its own, often so complicated that many organists would find it difficult to play with their five fingers. To these qualities must be added the exquisite art Bach displayed in combining the stops of the Organ. His registration frequently astonished organists and Organ builders, who ridiculed it at first, but were obliged in the end to admit its admirable results and to confess that the Organ gained in richness and sonority.(132)