The title translates as "actions through probability". In the case of "Pithoprakta," this relates to Jacob Bernoulli's law of large numbers which states that as the number of occurrences of a chance event increases, the more the average outcome approaches a determinate end. The piece is based on the statistical mechanics of gases, Gauss's law, or Brownian motion. Each instrument is conceived as a molecule obeying the Maxwell–Boltzmann distribution law, with Gaussian distribution of temperature fluctuation. This theory states that "the temperature of a gas derives from the independent movement of its molecules." Xenakis drew an analogy between the movement of a gas molecule through space and that of a string instrument through its pitch range. To construct the seething movement of the piece, he governed the 'molecules' according to a coherent sequence of imaginary temperatures and pressures. Brownian motion is a four-dimensional phenomenon (three-dimensions and time), and Xenakis created the score by first creating a two-dimensional graph, necessitating some simplifications. The abscissa (x) represents time at 5 cm = 26 MM, while the ordinates (y) represent pitch at 1 semitone = .25 cm. When transcribed into musical notation 5 cm = 1 measure. This length is subdivided into three, four, and five equal parts, allowing for fine differences in duration, but also creating a steady pulse in each instrument part, reducing the rhythm of the random walk to steady footsteps; composer Simon Emmerson notes that this regularity is "impossible in reality and fails to use his ‘stochastic’ approach in this instance." Each part gets nowhere, but as a whole the mass's pitch is freely modulated and its speed determined "temperature" varies.
- Harley, James (2004). Xenakis: His Life in Music, p.13. Routledge. ISBN 0-415-97145-4.
- Ilias Chrissochoidis, Stavros Houliaras, and Christos Mitsakis, "Set theory in Xenakis' EONTA", in International Symposium Iannis Xenakis, ed. Anastasia Georgaki and Makis Solomos (Athens: The National and Kapodistrian University, 2005), 241–249.
- Xenakis, Iannis (1992). Formalized Music: Thought and Mathematics in Composition, p.15. ISBN 9781576470794.
- Emmerson, Simon (2007). Living Electronic Music, p.48. ISBN 9780754655480.
- Randel, Don Michael (1996). The Harvard Biographical Dictionary of Music, p.999. ISBN 9780674372993.