“…The relevance of dynamical instability and ergodicity 2 to Statistical Mechanics (SM) has been sometimes questioned, [Farquhar 1964], but it is by now generally accepted that the unpredictability implied by Chaos is a natural ingredient to justify the statistical description of mdf dynamical systems. As stressed in the introduction, however, there is no rigorous, or even convincing, prove of any direct relationship between the instability times, as can be derived from dynamics (Lyapunov exponents, Kolomogorov-Sinai entropy,...) and the time-scales related to a Statistical Mechanical treatment, i.e., those belonging under the name of relaxation times.…”