Of the other chorales in the _Orgelbüchlein_, a small number, it is true, recall chorales by the organists of the North German school; as examples of this style we would cite _Wenn wir in höchsten Nöthen sein_ and _Wer nur den lieben Gott lässt walten_, both, in the ornamentation of their melodies, characteristic of the Reinkens and Buxtehudes. Finally, we would call attention, in _Ich ruf' zu Dir, Herr Jesu Christ_, to a form of writing truly instrumental, at the same time as analogous to the style of the _Adagio_ (in _A_ minor) of the Toccata in _C_ major, as the repetitions of notes are characteristic of G. Böhm.[135] [Footnote 135: Compare that chorale with this fragment of a chorale by Böhm, _Vater unser im Himmelreich_: [Music]] II The chorales of the Orgelbüchlein were compiled by Bach for purposes of instruction, as we have seen. It is not known whether it was his intention to publish them, or the eighteen _Choralvorspiele_[136]--sixteen autographs and two copies in Altnikol's hand--the MSS. of which are preserved in Berlin. In any case, these latter would have been rather for personal use than to serve as exercises for his pupils. [Footnote 136: P. vi, and vii. B.-G. xxv, vol. ii, 3rd part.] In this collection a form of chorale arrangement is found which we did not encounter in the _Orgelbüchlein_, the _trio_.[137] From a subject taken from a chorale melody, Bach forms a figure, which he develops in three parts in the style of the sonatas for two manuals and pedal; fragments of the _cantus firmus_ recur in these arabesques, sometimes repeated upon one after another of the manual keyboards, as an echo; or perhaps the pedal finally lays hold of them, entirely reconstructing the chorale--a stately cadence. What Bach calls a "Fantasia"[138] is of analogous character; the difference being, that the parts are more numerous, and no longer confined to a strictly continuous design. [Footnote 137: For example, upon the melodies "_Allein Gott in der Höh' sei Ehr'_" (several versions), "_Nun komm, der Heiden Heiland_" and "_Herr Jesus Christ, dich zu uns wend_."] [Footnote 138: _Nun komm, der Heiden Heiland._] A fusion of Pachelbel's style with that of the organists of the North, although modified, furnishes a new type: the melody is figured, it is true, but very discreetly; and the phrases of which it is composed are treated separately, each being preceded by a counterpoint derived from itself. The chorale _An Wasserflüssen Babylons_[139] (_super flumina Babylonis_), for example, is thus written. The _cantus firmus_ is sustained by the tenor, almost without elaboration, supported by rich polyphonic imitations of these various motives.