Ornaments are discussed in theoretical sources that range from pedagogic works (such as Herbst, I1642, 3/1658, and Walther, I1708) to encyclopedic compendia (PraetoriusSM, WaltherML) and comprehensive treatises on specific instruments or the voice (Quantz, I1752; C.P.E. Bach, I1753–62; Agricola, I1757). In addition, ornament tables and verbal explanations of ornament signs are included in many printed and manuscript sources of keyboard music, especially after 1700 (see §(v)(a) below). The music itself frequently provides suggestions for the performance of ornaments and the realization of ornament signs.
The 17th-century theoretical sources are almost exclusively vocal and italianate in orientation, intended to convey to Germany the innovations of Caccini, Monteverdi and other early Baroque Italian musicians. Bernhard and Mylius (I1685) document the continuation of the Italian tradition at, for example, the Dresden court under Bernhard's teacher Schütz. Elements of 17th-century terminology and teaching persist in later treatises, many of which are highly retrospective.
Prefaces and ornament tables accompanying published compositions are the chief sources on instrumental ornamentation until the very end of the period. Important early examples are Georg Muffat's introductions to his publications of music for keyboard (1690) and for instrumental ensemble (1698). Following the practice of Chambonnières and later French composers, J.C.F. Fischer published an ornament table in his 1696 volume of keyboard suites; Bach included a table similarly derived from French models in the manuscript Clavier-Büchlein for his son Wilhelm Friedemann (1720).
Apart from Mattheson (I1739), the major German treatises of the 18th century offer little on ornamentation until shortly after 1750, when the Berlin publications of Quantz (on the flute), C.P.E. Bach (on keyboard instruments) and Agricola (on singing) provided thorough accounts of the execution of various ornaments and the appropriate contexts for each. Leopold Mozart's violin treatise (I1756) agrees with the Berlin treatises on most fundamental points concerning ornamentation. Modern authors have been strongly influenced by these treatises, whose rationalistic accounts appeal to students seeking ‘correct’ realizations of Baroque ornament signs. But the immediate orientation of these writers is mid-century secular music in the galant style, and thus their advice cannot be applied automatically to earlier repertories. Moreover, it is misleading to apply their terminology in older music. For example, 17th-century sources had no single expression for what came to be called the trill, and the latter word had several distinct meanings.
Donington (A1963, 4/1989) presents a coherent interpretation of Baroque ornamentation, derived in part from the late German sources mentioned above. Neumann (I1978) argues for greater diversity of interpretation, based on a systematic study of the available sources. (Donington, pp.620–40, replies to some of Neumann's more controversial conclusions.) Butt (I1994) includes an analysis of German Baroque theory and pedagogy on ornamentation, especially in vocal music.
Broadly speaking, German Baroque ornamentation closely imitated contemporary Italian practices during the earlier part of the period, particularly in vocal music; adopted French practices and ornament signs beginning in the later 17th century, especially in keyboard music; and synthesized these two foreign traditions during the 18th century. German Baroque music followed general European trends in the gradual increase in the number and specificity of written indications for ornaments in musical scores, as well as in a proliferation of distinct ornament types as described in theoretical sources. In addition, there was a shift in the prevailing harmonic function of ornaments: whereas earlier ornamentation consists predominantly of the insertion of passing notes between consonances, later ornaments frequently commence on accented dissonances, used for expressive effect.
17th-century treatises discuss the stylized decoration of individual notes alongside more elaborate types of embellishment derived from the Renaissance practice of diminution. The two types of ornamentation become more distinct in 18th-century sources. Although early composers often failed to notate any ornamentation, the regular presentation of both types in 17th-century treatises implies that they were habitually improvised, at least by soloists.
Virtuosos continued to improvise elaborate embellishments in Italian-style music through the 18th century. Like Printz (I1676–7) and Niedt (I1700), Quantz provided numerous examples of embellishments on simple melodic intervals, and together with C.P.E. Bach and Agricola devoted considerable attention to cadenzas and other forms of improvisation. Music in the French style provided fewer opportunities for elaborate soloistic embellishment, instead favouring ornaments on single notes that could be designated by signs. Georg Muffat and later composers of French-style instrumental music evidently envisaged an approach to ornamentation modelled on Lully’s, in which an entire instrumental ensemble might perform ornaments uniformly, with little or no improvisation. Nevertheless, except in works for solo keyboard, explicit ornament signs remain rare until after 1750, apart from the abbreviation ‘t’ or ‘tr’ and the cross (+) sign. Ensemble musicians were evidently expected to select ornaments on the basis of their understanding of style (or by following a leader's instructions).
J.S. Bach, the Muffats (father and son) and others followed French contemporaries in scrupulously marking ornaments in their printed editions of keyboard music. But manuscripts are often less explicit, suggesting that the addition of ornament signs was a notational refinement, carried out for the benefit of students and the public. Copyists and music engravers often altered signs from those given by the composers, who were themselves not always consistent in their use of ornament signs: some signs given in ornament tables appear rarely in actual scores; occasionally, too, one finds several different signs used for the same effect. Each of these factors creates ambiguity for editors and performers, despite the apparently explicit notation of ornaments in 18th-century keyboard music.
To what degree French ornaments entered German singing is unclear, although the strong French element in many compositions must have had some influence on singers, as in the many arias from Bach's cantatas employing French dance rhythms. The ornaments described by Agricola – whose work is an annotated translation of Tosi's 1723 Italian treatise – are not in fact very distant from François Couperin's, although they are employed in a different stylistic context. But vocal music never became as explicit as instrumental in indicating ornaments. Although some relatively early treatises (e.g. Bernhard and Mylius) used letters and symbols to represent certain vocal ornaments, these never caught on; most singers evidently relied instead on their knowledge of style.