If we want to have a stable system, such as a living system, there must be a way to get rid of this thermal energy, otherwise the temperature will raise higher and higher until rampant agents of thermal motion kill all organization around. We come to the conclusion that if we want to see a stable or growing organization, there must be a relatively small number of agents which maintain the organization, passing to it in the process some energy, which later escapes the system as thermal energy. It is often thought that the lower the energy of a system is, the more stable it is, but this is not accurate. A system may be in a state with relatively low energy but surrounded by low potential barrier. It will have much greater probability to jump some place than the same system in a state with a higher equilibrium energy, but surrounded by a high potential barrier.
Stability is a feature of the configuration-energy function of the system.
Theoretically, it is this function that is studied by cyberneticians and biologists. We are interested in the structure of the energy function of systems, the existence of local minima well protected by potential barriers. Evolution, and life itself, is the wandering of the system around local minima, in search of more and more protected configurations. The forms of matter we see in nature are subsets of the total set of all possible configurations of any physical system. Stability of a form is measured by how long a configuration remains in its subset.