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.
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.
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.
In the same style of composition, born of a poetic imagination, is the chorale-prelude Schmücke dich, O liebe Seele.
"Schmücke dich, O liebe Seele!" Adorn thyself, O dear soul; be full of virtue, to please God; yet, however pure, may thy virtue be natural and effortless! Be full of grace, and may thy virtue be a very beautiful thing; doubtless thou hast never sinned, and thus there is no question of repentance ... that would evoke some feeling of sadness, and no sadness whatsoever can exist here; thou art already very noble, and thou must become still more noble; already very limpid, thou must become still more limpid; although far from the earth, arise now towards the heavens.... Sublime as thou art, thou must become divine. Let thy virtue be a very beautiful thing!
"Schmücke dich, o liebe Seele!" Adorn thyself, O dear soul! And Johann Sebastian treats a single line of the very calm and too austere chorale. Its robes of sackcloth being somewhat too severe, he bedecks it with simple and suave ornaments, like lilies which would live on a plain and naked altar. So might a learned and holy priest speak those words which at once charm and sanctify; and his hands do not remain crossed upon his breast, but his gesture mounts upwards towards God, scarcely saddened by a separation which soon will cease ... virtue is a joyful thing!
"Schmücke dich, o liebe Seele!" Adorn thyself, O dear soul. And now, suddenly, upon a distant manual, the calm and less severe chorale is heard. Do those voices mount towards God, or do they call from heaven? Is it a prayer which rises, or the dew of a grace which softly falls like the rain? And the suave ornaments of a simple melody thus live like lilies, and breathe no sadness. For virtue is beautiful and joyous.... "Schmücke dich, o liebe Seele!" Adorn thyself, O dear soul!
Bach wrote this chorale on a Sunday, as a pious man conceives in his heart a beautiful and childlike prayer, for the heavens are very pure on that day, and one's soul is wholly sincere.[140]