Purity of heart is health to the soul; it also gives light to the understanding. The chaste are like a crystal without flaw, or a clear, gently-flowing stream, in which the face of heaven is mirrored. Purity of heart, interior brightness and angelic freedom aid to the attainment of wisdom; it imparts knowledge to savants and teachers, to philosophers and theologians.
THE CATECHISM EXPLAINED, An Exhaustive Explanation of the Catholic Religion
