This is, of course, to be understood as in the Athanasian Creed. The attributes of eternity, omnipotence, etc., are ascribed to each of the Three Persons, and we are then told that there are not three Eternals, etc. Each Person of the Holy Trinity possesses each attribute, but the attributes are all one and cannot be divided any more than the Godhead. Each Person is holy, but there are not, so to say, three separate Holinesses.
Editorial footnote · On the Holy Spirit, Chapter XVI., editorial note cite_note-1 · Original source