In about 1970 the achievement of the activated chemical vapor deposition (CVD) diamond synthesis under low-pressure had been regarded as “alchemy” and thermodynamically impossible, although it is the case that only diamond films and tiny diamond crystals were obtained at that time. After about 30 years, however, beautiful 10-carat-sized, gemquality single-crystal synthetic diamonds can already be obtained by the similar process under low-pressure. Such a thermodynamics enigma should still be explained by the thermodynamic coupling model which was proposed by us in 1990. This model arose as a result of the severe restriction of classical thermodynamics based on the Carnot theorem and Clausius’ cyclical-process assumption. At the same time, Clausius’ “compensation” (now called thermodynamic coupling) for complex systems, including biological processes and living systems, comes to our attention in the current 21st century. The existing living systems do not only agree with nature laws but also skillfully utilize natural laws, including the second law of thermodynamics. Finally, modern thermodynamics based on the extended Carnot theorem (or the nonequilibrium nondissipative principle) appears.