More on Prayer from Augustine

This is part of Augustine's letter to Proba (from today's Office of Readings). It offers a wonderful insight on the Spirit's "groan" in the believer:

We do not know what is right to pray for, but the Spirit himself pleads with sighs too deep for words...

We must not understand by this that the Holy Spirit of God pleads for the saints as if he were someone different from what God is: in the the Trinity the Spirit is the unchangeable God and one God with the Father and the Son. Scripture says: He pleads for the saints because he moves the saints to plead, just as it says: The Lord your God tests you, to know if you love him, in this sense, that he does it to enable you to know. So the Spirit moves the saints to plead with sighs too deep for words by inspiring in them a desire for the great and as yet unknown reality that we look forward to with patience. How can words express what we desire when it remains unknown? If we were entirely ignorant of it we would not desire it; again, we would not desire it or seek it with sighs, if we were able to see it.