Extract from : Andrew Infanti: Cultural and historical models in the piano works of François-Bernard Mâche

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The piano cycle 
At the heart of the scattered constellation we have just hastily inventoried lies a "pianistic cycle" of seven compositions: a variable-geometry arrangement that can be freely recomposed according to the theme, duration and character chosen. The core of the cycle is formed by the three compositions evoking the rivers of hell in Greek mythology - Styx, Lèthè and Achéron. But the theme of night could also be included, with Nocturne and Mesarthim, for example. We could also evoke the "natural phenomena observed by Arab scholars", illustrated by the duo Areg (plural of dunes) and Mesarthim (same name in Hebrew and Arabic), and so on. 
The tonal "centers of gravity" of each piece also lend themselves to an integral presentation, arranged like a "cycle" of old-time lieder. Thus, the rising B-F sharp in Areg prepares the central tone of Mesarthim (F sharp), whose gentle pulsations continue in the superimposed ninths of Lèthè. The insistence on A in Styx is continued in Nocturne, which ultimately favors the D note. The note D then marks the beginning of Medusa, whose violent, erratic course paves the way for the world of murmur and noise elaborated in Acheron. Other arrangements are possible, such as "increasing" or "decreasing" cycles in the number of performers.... 

...A similar mass effect is further accentuated in Lèthè for two pianos, eight hands. This veritable quartet evokes a kind of "ritual of oblivion" and proposes, through several pianistic schemes, an alternative to the model of historical subjectivity. A terrifying sonic image, that of a river in flood, is produced by the wide range of independent movements made by the four performers, each entering in turn, engaging in a terrifying collective accelerando, right up to the moment when they individually pursue this regain of speed6. The truth of the situation, however, lies in the coda of the piece, where individual subjectivity is exposed as forgetting itself - through a melody that disintegrates on its own7.

5 I must mention here the excellent article on the "cycle pianistique" by Geneviève Mathon in Cahiers du ClREM(Rouen), n°22-23, 1991-92, pp. 65-72. 
6 Lèthè, Paris, Durand, 1985, p. 9-11. 
7 Ibid. p. 13.