Book 2, CHAPTER 4: A Pure Mind and Simple Intention
Comment: “Blessed are the pure of heart, for they shall see God,” 
says our Savior (Matt 5:8). This reflection is a means to that end. Thomas advises us to look for the goodness and beauty in all things and stay away from “unhealthy affections.” Instead we should seek out the will of God especially where it can benefit our neighbors. When we take on this purity of heart, we see things as Christ sees them. The scales fall from our eyes and the Creator is revealed in the smallest and “ugliest” of things. However, if we persist in our sin, we only see the nasty, degraded nature of things. On our journey, as we become more fervent, we conquer our self and, achieving victory, count as nothing the labors of the journey. “Create in me a clean heart, O God.” (Ps 51:10)
Chapter 4, In Short.
1. You are lifted above earthly things when you have simplicity and purity.
2. A pure heart penetrates heaven and hell.
3. Lukewarm believers fear the task of conquering the self, but when fervent, do not recollect the difficulties.
Book 2, Chapter 4: A Pure Mind and Simple Intention
1. With two wings a disciple is lifted above earthly things: that is, with simplicity and purity.
Simplicity ought to be in the intention, purity in the affection.
Simplicity reaches towards God, purity takes hold of Him and tastes Him (John 6:35; Matt 26:26-27).
You will not be hindered by good action if you are free from unhealthy affections. You will enjoy inward liberty if you reach after and seek only the will of God and the benefit of your neighbor.
When your heart is right, then every creature will act as a mirror of
life and a book of holy doctrine (Acts 9:18). There is no creature so small and vile that cannot yet manifest to us the goodness of God (Rm 8:19).
2. If you were good and pure within, then you would you look upon all things without hurt and understand them rightly.
A pure heart penetrates heaven and hell.
As you are inwardly, so you judge outwardly. If there is joy in the world surely the disciple who is of pure heart possesses this joy. And if there is tribulation and anguish anywhere, the evil conscience feels the best of it (Rm 11:9).
As iron cast into the fire loses rust and is made all bright with burning, so the believer who turns wholly to God is freed from laziness and is changed into a new disciple (Prv 27:17).
3. When a believer begins to grow lukewarm (Rev 3:16), the fear of a little labor develops, and soon outward consolation is accepted. But when the task is set to conquer one’s self and to walk courageously in the way of God, then you may counts as nothing those things which before seemed to be so difficult to you.