To examine the manner in which molecular dynamics of a polymerizing liquid (stoichiometric amounts of 4,4'-diaminodicyclohexylamine and diglycidyl ether of bisphenol-A) evolves during thermal cycling from its (molecular) vitreous state to its fully polymerized vitreous state, calorimetry, and dielectric spectrometry were performed simultaneously in real time. The half-width of the relaxation spectrum of the liquid was relatively narrow and became narrower on heating. This was followed by an increase in the characteristic relaxation time and the spectrum became broader as polymerization occurred and reached completion. The dc conductivity initially increased and then decreased. The faster dynamics of the Johari-Goldstein relaxation in the fully polymerized state evolved as polymerization reached completion and the temperature increased. The dielectric polarization associated with this relaxation had a broad spectrum, whose half-width increased with decrease in the temperature. Its relaxation rate followed the Arrhenius equation with an activation energy of 63.4 kJ/mol. The temperature dependence of the faster relaxation did not change with the change in the overall configurational entropy of the liquid, a feature that substantiates the dynamic heterogeneity theories for the structure of the liquid and for the origin of the relaxation.