God manifests Himself through His actions or energy. "Claiming that we know our God in His energies, we do not promise to draw close to Him in His very essence. For if His energies come down to us, His essence remains inaccessible ", - says St.. Basil the Great. This is the place of the letter to Amphilochius  along with other texts 'Against Eunomius'  will be of paramount importance in the study of the vision of God. Byzantine theologians, in formulating the distinction between essence inaccessible - ????? - And its natural origin - ????????? - Or having an action will often refer to the authority of these texts.