No attempt is here made at chronological sequence. The changes in Bach's style, though clear and important, are almost impossible to describe in untechnical language; nor are they of such general interest as to make it worth while to expand this summary by an attempt to apportion its contents among the Arnstadt-Mühlhausen period, the Weimar period, the Cöthen period (chiefly remarkable for instrumental music and comparatively uninteresting in its easy-going choral music), and the last period (1733-1750) in which, while the choral works became at once more numerous and more terse (e.g. Jesu, der du meine Seele) the instrumental music, though never diffuse, shows an increasing preference for designs on a large scale. (Compare, for example, the second book of the Wohltemperirtes Klavier, 1744, with the first, 1722.)
I. - Church Music
A. With Orchestra
190 church cantatas: besides several which are only known from fragmentary sets of parts. Of the 190, 40 are for solo voices, about 60 (including some solo cantatas) are more or less founded on chorales, and the rest, though almost invariably containing a chorale (for congregational singing), are practically short oratorios and frequently so entitled by Bach himself.
3 wedding cantatas: the Easter oratorio (exactly like the above-mentioned oratorio-cantatas; and the Christmas oratorio (six similar cantatas forming a connected design for performance on six separate days).
The Passions according to St Matthew and St John.
Funeral ode for the Duchess Eberhardine (now known to be arranged from portions of the lost Passion according to St Mark).
4 short masses (i.e. Kyrie and Gloria only) mainly compiled from church cantatas.
Mass in B minor. Magnificat in D. A few other ecclesiastical Latin choruses.
B. Without Orchestra
5 motets a capella (but there is reason to believe that these, except Komm Jesu komm, were intended to be partly supported by the organ). A sixth motet has an obligato figured-bass accompaniment.
A few early choruses, mostly turned to account in later works.
A large collection of plain chorales, including several original melodies.
II. - Secular Vocal Music
Der Streit zwischen Phoebus und Pan and Der zufrieden gestellte Aeolus; both entitled Dramma per Musica, but showing no more essential connexion with the stage than Handel's Acis and Galatea.
7 solo and 7 choral cantatas, of which latter three were almost entirely absorbed into the Christmas oratorio and the B minor mass. Of the solo cantatas two are Italian (one of these being Bach's only developed work for voice and clavier) and two are burlesque.
Several tunes with clavier bass, almost foreshadowing the modern song.
III. Instrumental Music
7 clavier concertos arranged from violin concertos and other sources.
3 concertos for two claviers (two being arranged from concertos for two violins).
2 concertos for three claviers.
The 6 Brandenburg concertos, for various combinations.
2 violin concertos, and a colossal torso of a concerted violin-movement forming the prelude to a lost church cantata.
1 concerto for two violins.
4 orchestral suites. (The symphony in F in the same volume of the B. G. is only an earlier version of the first Brandenburg concerto.)
B. Chamber Music
3 sonatas for clavier and flute; a suite and 6 sonatas for clavier and violin, 3 for clavier and viola da gamba; 2 trios with figured bass; 2 flute-sonatas and a violin suite with figured bass; 6 sonatas (i.e. 3 sonatas and 3 partitas) for violin alone; 6 suites for violoncello alone.
C. Clavier and Organ Music
Bach's own collections are: -
1. Das wohltemperirte Klavier for clavichord: two books each containing 24 preludes and fugues, one in each major and minor key; with the object of stimulating tuning by "equal temperament" instead of sacrificing the euphony of remoter keys to that of the more usual ones.
2. Klavier-übung (chiefly for harpsichord) in four books comprising: (i.) 15 two-part inventions and 15 three-part symphonies, (ii.) 6 partitas, (iii.) The "Goldberg" variations. 4 duets, and an important collection of organ choral-preludes, with the "St Anne" prelude and fugue in E flat, (iv.) The Italian concerto and French overture.
3. The 6 "French" and 6 "English" suites.
The other clavier works fill two Jahrgänge of the B.-G.
Bach's collections of organ music are (besides that included in the third part of the Klavier-übung): - (1) 6 sonatas. (2) 4 groups of 6 organ preludes and fugues. (3) Das Orgelbüchlein, a collection of short choral-preludes carefully planned - all the blank pages of the autograph being headed with the titles of the chorales intended for them - but not half executed. (The projected whole would have been a larger volume than the Wohltemperirtes Klavier). (4) 18 larger chorale-preludes, including Bach's last composition. (5) The 6 "Schübler" chorales, all arranged from movements of cantatas.
Besides these there are the three great independent toccatas and the Passacaglia. The remaining choral-preludes fill one Jahrgang, and the other organ works two more.
Two important instrumental works cannot be classified, viz. Das musikalische Opfer, the volume of compositions (two great fugues, various puzzle-canons, and a splendid trio for flute, violin and figured bass) on the theme given to Bach by Frederick the Great; and Die Kunst der Fuge, a progressive series of fugues on one and the same subject, written in open score as if entirely abstract studies, but all (except the extreme contrapuntal tours de force) in admirable clavier style and of great musical value.
IV. - Lost Works
J. N. Forkel's statement that Bach wrote 5 Jahrgange of church cantatas (i.e. enough to provide one for each Sunday and holy day for five years) would indicate that some 80 are lost, but there is reason to believe that this is a great exaggeration. Not more than six or seven cantatas are known to be lost, by the evidence of fragments, text-books, etc.
Forkel also says that Bach wrote five Passions. Besides the great Matthew and John Passions there is in an indisputable Bach autograph one according to St Luke; but it is so worthless that the best plea for its authenticity offered by responsible critics is that only a personal interest could have induced Bach to make a copy of it.
The lost Passion according to St Mark must, judging by the movements preserved in the Trauer-Ode, have been larger than that according to St John.
Was there a genuine Lucas-Passion? If so, Forkel's report of five Passions would be explained. Several lost secular works are partly preserved in those portions of the Christmas oratorio of which the sources are not definitely known, but which, like the other duplicated numbers, are fair copies in the autograph.
Three violin concertos and one for two violins; known only from the wonderful clavier versions.
Most of the first movement of the A major sonata for clavier and flute which was written in the spare staves at the bottom of a larger score. Some of these have been cut off.
V. - Arrangements of Works by other Composers
Arrangements for harpsichord alone of 16 concertos, generally described as by Vivaldi, but including several by other composers.
4 Vivaldi concertos arranged for organ.
Many of these arrangements contain much original matter, such as entirely new slow movements, large cadenzas, etc.
Concerto in A minor for 4 claviers and orchestra, from Vivaldi's B minor concerto for 4 violins. This, though the most faithful to its original, is the richest and most Bach-like of all these arrangements, and is well worth performing in public.
2 sonatas from the Hortus Musicus of Reinken, arranged for clavier. (The ends of the slow movements are Bach.)
Finishing touches to cantatas by his uncle Johann Ludwig Bach. Also a very characteristic complete "Christe eleison" inserted in Kyrie of Johann Ludwig's.
VI. - Doubtful and Spurious Works
Bach's autographs give the name of the composer on the outside sheet only. He was constantly making copies of all that interested him; and where the outside sheet is lost, only the music itself can tell us whether it is his or not. The above-mentioned Passion according to St Luke is the chief case in point. The little music-books he and his second wife wrote for their children are full of pieces in the most various styles, and the editors of the Bach-Gesellschaft have not completely identified them, even Couperin's well-known "Les Bergeries" escaping their scrutiny. A sonata for two claviers by Bach's eldest son, Wilhelm Friedermann, was detected by the editors after its inclusion in Jahrgang xliv. The second of the 3 sonatas for clavier and flute is extremely suggestive of Bach's sons, but Philipp Emanuel ascribes it to his father. However, he might easily have docketed it wrongly while arranging copies of his father's works. It has a twin brother (B.-G. ix. Anhang ii.) for which he has not vouched.
Four absurd church cantatas are printed for conscience' sake in Jahrgang xliii. More important than these, because by no means too obviously ridiculous to deceive a careless listener, is the well-known 8-part motet, Lob, Ehr' und Weisheit (blessing and glory and wisdom). A closer acquaintance shows that it is really very poor stuff; and it was finally crowned with absurdity by the discovery that its composer was a contemporary of Bach, - and that his name was Wagner.
The beautiful motet, Ich lasse dich nicht, has long been known to be by one of Bach's uncles (Johann Christoph).