 In the 1870s Boltzmann offered an important answer to this  question.[15]  At the heart of his answer lies the idea to assign probabilities to macrostates according to their size. So Boltzmann adopted the following postulate: \(p(M_j) = c\mu(M_j)\) for all \(j = 1,\ldots ,k\), where \(c\) is a normalisation constant assuring that the probabilities add up to one. Granted this postulate, it follows immediately that the most likely state is the equilibrium state (since the equilibrium state occupies the largest chunk of the phase space). From this point of view it seems natural to understand the approach to equilibrium as the evolution from an unlikely macrostate to a more likely macrostate and finally to the most likely macro-state. This, Boltzmann argued, was a statistical justification of the Second Law of thermodynamics.