Which thermodynamic reasoning approach did the founders of thermodynamics favor ?
The notion of a cyclic process does not require a full account of the state of the system , but does require a full account of how the process occasions transfers of matter and energy between the principal system ( which is often called the " working body " ) and its surroundings , which must include at least two heat reservoirs at different known and fixed temperatures , one hotter than the principal system and the other colder than it , as well as a reservoir that can receive energy from the system as work and can do work on the system .