Chapter 10 — Part I: The Creed — Article VIII: I Believe in the Holy Ghost
Section 24. Our Lord said, at His Last Supper: When the Paraclete cometh whom I will send you, the Spirit of truth, who proceedeth from the Father, he shall give testimony of me. On another occasion, that the Holy Ghost will be sent by the Father, He declares in these words: whom the Father will send in my name. Understanding these words to denote the procession of the Holy Ghost, we come to the inevitable conclusion that He proceeds from both Father and Son.