) ≥ 0 where ∆𝐺 is a change in the free energy of reaction and the subscript "eq" refers to an equilibrium value, the others having the same meanings as mentioned in the Results section. The equilibrium of reaction is given by 𝐴 = -∆𝐺 = 0. Thus, to what extent a reaction is close to equilibrium can be evaluated by the magnitude of the affinity 𝐴 or the thermodynamic force 𝐴 𝑇 ⁄ . This argument applies to a reaction in an ORN if we consider the magnitude of 𝐴 or 𝐴 𝑇 ⁄ per reaction. Now, for a steady state of an ORN, the concentrations of chemical substances are kept constant by a full balance between all the reactions and thus the steady state does not approach equilibrium even if reactions proceed, contrary to the case of an individual reaction. However, a steady state of an ORN has a possibility of approaching equilibrium through an inflow of an efficient catalyst into an ORN and an increase in the rate constant 𝑘 f of the forward reaction process in it. This is because an increase in 𝑘 f leads to an increase in the rate of the forward reaction process and hence to decreases in the concentrations of the reactants of the reaction, which in turn lead to the reorganization of the ORN and the formation of a new steady state. Such decreases in the concentrations of the reactants of the reaction necessarily lead to a decrease in the affinity 𝐴 for the reactions in the ORN because otherwise such decreases would not occur because of the second law of thermodynamics. Thus, the reorganization of the ORN driven by such decreases as the driving force should lead to a decrease in the affinity 𝐴 per reaction in a new steady state, compared with the original steady state. This consideration indicates that an increase in the rate or the rate constant of a reaction in an ORN acts as an important factor in an approach of a non-equilibrium steady state to equilibrium. In fact, if the rates of reactions in an ORN become much higher than those of inflows of source substances and outflows of reaction products, the ORN reaches a state nearly the same as an equilibrium state. Note here that an increase in the rate or the rate constant of a reaction in an ORN is achieved by the formation of an efficient catalyst or reaction site, which is in most cases accomplished by the formation of molecules or molecular aggregates with highly ordered structures. Thus, it is reasonable to assume that a non-equilibrium steady state of an ORN can evolve toward a highly ordered and high-function state through interaction with the environment.