An Exposition of the Orthodox Faith 37

1 BOOK II — CHAPTER 23: Concerning Energy.

2 All the faculties we have already discussed, both those of knowledge and those of life, both the natural and the artificial, are, it is to be noted, called energies. For energy is the natural force and activity of each essence: or again, natural energy is the activity innate in every essence: and so, clearly, things that have the same essence have also the same energy, and things that have different natures have also different energies. For no essence can be devoid of natural energy.

3 The primal and only true energy of nature is the voluntary or rational and independent life which constitutes our humanity. Energy is drastic activity of nature: and by drastic is meant that which is moved of itself.