Isaiah 30:19

These two then, namely, the grace of God and free will, seem opposed to each other but really are in harmony. And we gather from the system of goodness that we ought to have both alike, lest if we withdraw one of them from man, we may seem to have broken the rule of the church's faith. For when God sees us inclined to will what is good, he meets, guides and strengthens us. For "at the voice of your cry, as soon as he shall hear, he will answer you"; and "Call upon me," he said, "in the day of tribulation, and I will deliver you, and you shall glorify me." And again, if he finds that we are unwilling or have grown cold, he stirs our hearts with salutary exhortations, by which a good will is either renewed or formed in us.

(Verse 19) For the people of Zion will dwell in Jerusalem. The Jews refer these things to the time of Cyrus, when the people returned from Babylon to Judaea under Zerubbabel and the high priest Joshua. But we, as we have often said already, refer all the promises that surpass the mediocrity of that time to the coming of Christ, in which the once captive people, freed by the passion of the Lord, dwelled in Zion and Jerusalem, namely, in the watchtower and vision of peace, that is, in the Church. Furthermore, that which is added in the Septuagint as a word of sanctity, they said: 'For a holy people dwells in Zion' (alternative: will dwell), we can interpret it to mean that no one dwells in Zion unless they are holy and hear the Lord saying, 'Be holy, for I am holy' (Leviticus 11:44).

The divine protection, then, is always inseparably present to us, and so great is the love of the Creator for his creature that his providence not only stands by it but even goes constantly before it. The prophet, who has experienced this, confesses it very clearly when he says, "My God will go before me with his mercy." When he notices good will making an appearance in us, at once he enlightens and encourages it and spurs it on to salvation, giving increase to what he himself planted and saw arise from our own efforts. For, he says, "before they cry, I will hear them. I will hear them when they are still speaking." And again: "As soon as he hears the voice of your cry, he will respond to you." Not only does he graciously inspire holy desires, but also he arranges favorable moments in one's life and the possibility of good results, and he shows the way of salvation to those who are straying.