 The central kind of authenticity that has been discussed is authenticity with respect to the instantiation of the work. Most agree that the fullest such authenticity requires the production of the right pitches in the right order. Pure sonicists argue that this is sufficient (e.g., Kivy 1988a). Timbral sonicists argue that these pitches must also have timbres reflecting the composer’s instrumentation (e.g., Dodd 2007: 201–39). Instrumentalists argue that such sounds must be produced on the kinds of instruments specified in the score (e.g., Levinson 1990c). Much of the debate is over what kinds of aesthetic or artistic properties are essential to musical works. If the limpid textures of Bach’s Brandenburg Concerto No. 5 are essential to it, then one cannot authentically instance the work using a grand piano instead of a harpsichord. As such, the debate reflects a wider one in aesthetics, musical and otherwise, between formalists (or empiricists, or structuralists), who believe that the most important properties of a work are intrinsic ones, accessible to listeners unaware of the historical and artistic context in which it was created, and contextualists, who believe that a work is essentially tied to its context of creation. Stephen Davies has argued for a strong contextualism, claiming that one cannot give a single answer to the question of whether particular instrumentation is required for the fully authentic instantiation of a work. Works can be ontologically “thicker” or “thinner” as a result of the specifications of a composer working within certain conventions (1991, 2001). The more properties of an authentic performance a particular work specifies, the thicker it is. Thus for some works (typically earlier in the history of Western music) instrumentation is flexible, while for others (for example, Romantic symphonies) quite specific instrumentation is required for fully authentic performances.