“He will lead you into all truth”
The Holy Spirit, the Paraclete, the Advocate, is he whom the Father and the Son send like a breath into the souls of the just. It is by him that we are sanctified and made worthy of becoming saints. Human breath is the life of the body, divine breath is the life of the soul. Human breath makes us sensitive, divine breath makes us holy. This Spirit is Holy because without him no spirit, whether angelic or human, is able to be holy.
“The Father will send him to you in my name,” Jesus says (Jn 14:26), that is to say in my glory, to make my glory known. Or again, because he has the same name as the Son: he is God. “He will glorify me” because he will make you spiritual, understanding how the Son is equal to the Father and not just a man as you see him to be, or because he will take away your fear and cause you to proclaim my glory to the whole world. Thus man’s salvation is what my glory is.
“He will teach you all things.” “O children of Zion be glad!” says the prophet Joel, “For the Lord your God has given you the one who teaches righteousness” (2:23 Vulg.), he will teach all of you everything that pertains to salvation.