Understanding the temperature-dependent atomic dynamics of amorphous solids can be understood within the context of the structure of the potential-energy surface (PES). By comparing the experimental temperature-dependent results from a multitude of measurement techniques, it is clear that the observations must originate from a shared fundamental origin, in this case the PES, a concept originally proposed by Goldstein. The atomic dynamics can be fully described by interpretation of the consequence of the shape of the PES, and this picture provides a comprehensive connection to the previously suggested Coupling Model in order to explain the link between the fundamental dielectric relaxation processes and higher-frequency observations. By using ab initio molecular-dynamics simulations we are able to highlight the critical role that 'soft' interactions, such as intra-molecular torsional potentials, have on the glass-transition processes. Finally, we show that these principles can be used in applications by exciting amorphous molecular solids with high-power terahertz radiation, where it is possible to actively induce processes, such as crystallisation and atypical crystal-polymorph formation, by selectively perturbing the dynamics allowed by the shape of the PES. This study shows the important link to the PES for the understanding of amorphous solids. It further highlights the crucial role of weak forces for the material behaviour in applications as diverse as amorphous drug stability, durability of polymers and the solid electrolyte interphase of batteries amongst others.