We often conceive of the augmented sixth chord as a nineteenth-century phenomenon. A history of the augmented sixth, Mark Ellis's A Chord in Time focuses most of its attentions on Pre-Classical theory and music – areas under-represented by our analytical attentions. Beginning with repertory from the late sixteenth century, this study addresses a myriad of issues, from comparatively simple points on labelling systems (Ellis uses an asterisk) to more complicated matters of roots and inversions, the chord's roles in historical theories, and its varied functional profiles.

Organized chronologically, the early chapters provide a tutorial on the history and uses of the French, Italian, and German sixths. Chapter 1 (‘Key Concepts’) summarizes the harmonic qualities of the sonority, then widens the purview, placing the augmented sixths in the context of not just the gradual transition from modality to tonality, but alongside the development of the Phrygian cadence and another chromatic sonority, the Neapolitan sixth chord.Footnote 2 The second chapter (‘Natural Selection’) begins the historical evolution of the chords, ensconced in the reminder that evolution does not mean a smooth progression, but instead, a series of stops and starts.Footnote 3 A précis of the chord's uses throughout history (Table 2.1, p. 37) is especially helpful, and includes everything from the sonority that began life with an ascending passing tone between scale degrees 4 and 5 in minor, to the creative ‘colouristic’ uses by Richard Strauss. Chapter 3 (‘Painted Words’) summarizes the development from the early to late Baroque and demonstrates that the chord appears in a multitude of ways – not just the ones that foreshadow Classic-era usage.Footnote 4 We should not be surprised to learn that there are close parallels between the augmented sixth's early uses and the texts to which they were so often set; but that the sonority appears in both vocal and instrumental repertoire from the pre-Baroque and Baroque era also suggests that we should no longer be content to disregard all such moments as the product of text painting.

Chapter 4 (‘Harmony and Invention’) considers the almost-commonplace role of the augmented sixth by the early 1720s; Ellis contends that Vivaldi's La Stravaganza concertos (1714), along with changes of approach in contemporary theoretical writings and the solidification of tonality, help to bolster its use (p. 83). What makes this progression more striking in the Baroque are the contexts in which it often appears: in contradiction to common wisdom, what Ellis cleverly calls the ‘sharp inversion’ – 4 as the bass pitch, not ≅6 – begins here, not in the Romantic era. (Ellis also notes that this is ‘characteristically North European’. See p. 84.) Chapter 5, a conceptual companion chapter, elaborates on the augmented sixth's important personal stylistic role in the music of J.S. Bach – a role that does not always follow the norms of the High Baroque. Chapter 6 (curiously titled ‘The Science of Compassion’) describes how the chord gains a foothold in writings by George Muffat (d. 1704), Friedrich Marpurg (d. 1795) and Gottfried Weber (1779–1839), who represent three stages of development: acknowledging the interval itself; consolidating the chord into harmonic theory; and identifying the ambiguities inherent therein. Like his teacher Vogler (and Marpurg and Albrechtsberger before him), Weber derives the Italian augmented sixth from what he refers to as iv, the French sixth from the supertonic (with scale degree 2 as a sub-posed, implied pitch) and the German in similar fashion as the Italian sixth, except with a missing root and added ninth (p. 156). While Weber attaches a root – an issue to which I will return – he also addresses the potential for the German augmented sixth's harmonic and enharmonic ambiguities.

By 1790, the augmented sixth as a harbinger of important structural moments within the sonata form was not only popular but cliché. Chapter 7 (‘Classical Contexts’) details this progression, which begins with Haydn's use of the chord in modulations to the second key area, or before the dominant in the drive toward the recapitulation (curiously, a point that Charles Rosen seems not to make).Footnote 5 Consequently, the normative function of the augmented sixth is defined as a predominant (pp. 161–6). Yet, as Ellis notes at several points throughout the book, the term ‘augmented sixth chord’ should not be exclusive to the strong predominant to which we most commonly attach the term. It may instead refer to other common chromatic elements, in particular the so-called 5 dominant, in which an augmented sixth may form between the raised chordal fifth and the chordal seventh (D and F in the dominant of C major).

Chapters 8 and 9 (‘Triumph and Ambiguity’ and ‘Swansong’) codify nineteenth-century uses of the augmented sixths. In chapter 8, the importance of the sharp inversion returns, with Beethoven's late string quartets, and it is not limited to the traditionally predominant versions of the chord. Rather, near the end of the first movement of the Op. 131 quartet (Ellis's Ex. 8.5, reproduced here as Ex. 1), an ambiguous augmented sixth appears as a dominant of C minor.

Ex. 1 Beethoven, String Quartet in C minor, Op. 131, mvt. I, bars 111–116 [Ellis, Ex. 8.5, p. 190]

In bar 113, the chord contains a diminished third between B and D♮, which Ellis indicates has shades of the Neapolitan. While the C major triad at the movement's end (bars 116ff.) sounds more dominant than tonic to my ears – thus turning the sonority into a standard German sixth – Ellis acknowledges the uncertainty. At the end of this discussion, Ellis invites us to ponder further the root of this augmented sixth (p. 190). Given the chapter's direction, and some current scholarship on chromaticism, it seems pertinent to ask why we might continue to attach a root to a chord so often – and most effectively, as the author himself demonstrates with a minimalist label – defined without one.Footnote 6 The root derivation is not unusual, however. Ellis cites a passage by English theorist Alfred Day where, like Rameau, he derives the sonority from two roots: in C minor, the A♭ as a ninth above G, which he calls the ‘primary root’, and the F as the major third above the ‘secondary root’, D (p. 198). What makes the derivation curious is that he then identifies inversions to go along with this, including a ‘fourth inversion’, with an A♭ bass. Ellis notes that ‘[a]ccording to Day, augmented sixths are generally in [‘fourth’] inversion, because they are built on a minor ninth above the missing primary root’ (p. 198). How pleased a young Schoenberg – whose own writings would occasionally disregard the importance of roots – would have been to have discovered this after the riotous reaction to his own such sonority.Footnote 7

The book itself is beautifully produced, with clear, well-placed musical examples. At times, however, the prose would benefit from greater precision. The text identifies the first cadence in Chopin's F minor Nocturne, op. 55/1, in bars 14–16, but this phrase is a repetition of bars 1–8, at the end of which is a perfect authentic cadence (pp. 204–05).Footnote 8 The interesting discussion that follows could be enhanced by more consistent and specific identification of musical events with bar numbers, in particular, in the preparatory chords in bars 20–24 that include an augmented sixth (a chord I have not yet found).Footnote 9

With respect to the Brahms Passacaglia example, the issue is less one of imprecision than of incompleteness. (Ex. 9.2 has been reproduced as my Ex. 2, to which I have added additional analytical notation.)

While Ellis considers the opening six chords tonally ambiguous, I am not so sure, in part because my aural perception of the passage is so drastically different – fundamentally in E minor, with shades of the A minor Ellis finds so compelling. Example 9.2 considers the E major triad in the last measure a dominant; I hear it as a strong tonic. To be sure, the opening three chords are, to some extent, unusual in their expansion of plagal motion at the very beginning of a movement, but towards the end of the nineteenth century, this is unsurprising.Footnote 10 Likewise, the motion from the repetition of the A minor triad in bar 4, through a secondary dominant of the dominant, to a chord substituting for the cadential 6-4 is also fairly straightforward at this point in chromatic composition. The substitute cadential sonority then resolves linearly via a flat-two dominant, to the E major triad at the end of bar 8. Thus, while Ellis's hearing has its merits, I find it to be one of several possibilities that permeate the passage, adding complexity and depth to the Passacaglia; but it is not the most prominent one.

Ex. 2 Brahms, Symphony No. 4 in E minor, mvt. IV, bars 1–8 [Ellis, Ex. 9.2, p. 210]

Any discussion of chromaticism would be incomplete without a passage from the Tristan Prelude, and in Chapter 9, Ellis does not disappoint. He summarizes several other perspectives on the opening measures and provides his own reading of bars 2–3, as a French sixth resolving to the dominant in A minor (that is, the A is the chord-tone here, not the G). The explanation of its significance is satisfying, and connects the fleeting quaver to the identical pitch set, transposed, on the downbeat of bar 3, and to other moments within the Vorspiel. On the whole, the ninth and last chapter is impressive in its attempts to quantify how the highly chromatic music of Bruckner, Mahler, and Schoenberg use the sonorities, and how those uses differ. While these analyses will raise questions, Ellis is to be commended for including them at all, and much can be learned about how to consider this repertoire from this chapter.

Perhaps because of our great familiarity with the nineteenth-century augmented sixth, courtesy of Daniel Harrison and others, the value of this book is in its earlier chapters.Footnote 11 Nevertheless, Ellis does well by the nineteenth-century repertoire, by discussing passages and pieces that are often left untouched because of the extreme analytical difficulties they pose. For those interested in Common-Practice harmonic development, it is worth one's attention.