The peculiar relationship of the Son to the Father, such as we know it–we will find that the Spirit has this, to the Son. And since the Son says, “everything whatsoever that the Father has is mine (Jn 15:16),” we will discover all these things also in the Spirit, through the Son. And just as the Son was announced by the Father, who said, “This is My beloved Son, in whom I am well pleased (Matt 3:17),” so also is the Spirit of the Son; for, as the Apostle says, “He has sent the Spirit of His Son into our hearts, crying, ‘Abba! Father (Gal 4:6)!’” … Hence, if the Son, because of His peculiar relationship to the Father, and because of His being the Offspring of the Father’s own substance, is not a creature, but is of the same substance of the Father, then neither is the Holy Spirit a creature. To say otherwise were impious, because of His peculiar relationship to the Son, and because out of Him He is given to all, and what He has is of the Son. [St. Athanasius, *Four Letters to Serapion of Thmuis,