Euthymius Zigabenus, Panoplia Dogmatica; Theodoretus, Historia Religiosa

If He has the Word and the Spirit; accompanying Him and manifesting His activity; for indeed our word is not without spirit; which at the time of utterance, becomes the voice of our word; manifesting its power; but in our case, this spirit is alien to our essence; which is an inflow and outflow of air; but in the case of God Theou, as is the Word, not according to ours; but subsisting essentially; and of the same essence and nature % the Spirit as the Begetter, so also the Holy [Spirit], subsisting essentially; and has the same essence and nature and perfection as God Theou; proceeding from the Father Patros and being in Him; and accompanying the Word and the Son Hyios; and being His manifestor.

Exemplary proof of the same, marvelous, concerning the Father, and the Son, and the Holy Spirit:

A rubricated ornamental initial 'Ω' with vine-like flourishes. Just as the ray of the sun, and the light of the sun being separated, neither being divided from each other, come down even to us, so also the Son Hyios; and the Holy Spirit Pneuma; without distance and from the Father Patros and from each other, come down to us; working our salvation; and just as in those; the lamp accompanying the ray, is transmitted to us through that, so also the Holy Spirit Pneuma accompanying the Son Hyios, is transmitted through Him to the worthy; according to the transmission of the gifts; for in the gospels it says and He said; receive the Holy Spirit Pneuma; and just as in those, light is spoken of both of the sun and the ray, so also in these; Spirit is spoken of both of the Father Patros and of the Son Hyios elements.