[The term “beginning” (principium), when referring to the relation of the Trinity, or of any person of the Trinity, to the creature, denotes creative energy, whereby a new substance is originated from nothing. This is the reference in chapter 13. But when the term refers to the relations of the persons of the Trinity to each other, it denotes only a modifying energy, whereby an existing uncreated substance is communicated by generation and spiration. This is the reference in chapter 14. When it is said that the Father is the “beginning” of the Son, and the Father and Son are the “beginning” of the Spirit, it is not meant that the substance of the Son is created ex nihilo by the Father, and the substance of the Spirit is created by the Father and Son, but only that the Son by eternal generation receives from the Father the one uncreated and undivided substance of the Godhead, and the Spirit by eternal spiration receives the same numerical substance from the Father and Son. The term “beginning” relates not to the essence, but to the personal peculiarity. Sonship originates in fatherhood; but deity is unoriginated. The Son as the second person “begins” from the Father, because the Father communicates the essence to him. His sonship, not his deity or godhood, “begins” from the Father. And the same holds true of the term “beginning” as applied to the Holy Spirit. The “procession” of the Holy Spirit “begins” by spiration from the Father and Son, but not his deity or godhood.—W.G.T.S.]
Editorial footnote · On the Holy Trinity, Chapter 14.—The Father and the Son the Only Beginning (Principium) of the Holy Spirit.; original source section: Chapter 14, editorial note cite_note-7 · Original source