One of the most important features introduced by Eyring, Polanyi and Evans was the notion that activated complexes are in quasi-equilibrium with the reactants. The rate is then directly proportional to the concentration of these complexes multiplied by the frequency (kT/h) with which they are converted into products.  Below, a non-rigorous plausibility argument is given for the functional form of the Eyring equation.  However, the key statistical mechanical factor kT/h will not be justified, and the argument presented below does not constitute a true "derivation" of the Eyring equation.