Equilibrium thermodynamics - Callen's postulational approach

In order to provide the background for nonequilibrium thermodynamics, we outline the fundamentals of equilibrium thermodynamics. Equilibrium thermodynamics must not only be obtained as a special case of any acceptable nonequilibrium generalization but, through its shining example, it also elucidates the wide scope, the emphasis on universal relationships, and the advantages of a systematic postulational approach to nonequilibrium thermodynamics. Our outline follows Callen’s widely accepted, clearly structured approach as closely as possible.