  Instead, the context of his (1871b) makes clear enough how he intended the hypothesis, as has already been argued by (Brush 1976). Immediately preceding the section in which the hypothesis is introduced, Boltzmann discusses trajectories for a simple example: a two-dimensional harmonic oscillator with potential \(V(x,y) = ax^2 + by^2\). For this system, the configuration point \((x, y)\) moves through the surface of a rectangle.  See Figure 1 below. (See also Cercignani 1998, 148.) 