[...] The Psalter contains all of Scripture; the examples of the virtuous as well as the sinners, who through their repentance received God's grace, like David, who also received the prophetic gift.
A true treasury. Every verse is wisdom, correcting doctrines and leading to virtue.
With precision and brevity, it expresses the moral legislation of our lives.
"Turn away from evil and do good."
A method of repentance and a support in misfortunes.
The Psalms are peace for the soul, a conversation with God, a gathering of angels, and a repulsion of demons, an invincible weapon.
They are a heavenly Nile. They refresh the souls worn out by sin, who through poetry realize their mistakes, avoid them, and glorify God.
[...]
(from the book's introduction)