The answer
This expression confirms that the Holy Spirit proceeds from the Father eternally, just as the Son is born of Him eternally. When they say “through the Son,” they do not mean that the Son is inferior to the Father, but that the Spirit proceeds from the Father as a divine Hypostasis and is sent by the Son to give enlightenment and knowledge of divine mysteries; so that by Him, we enjoy the perfection of His work of salvation through our continuous sanctification and renewal.
Fr. Tadros Yacoub Malaty