53. The Ninth Commandment: You shall not indulge in impure thoughts or desires
After the disorder that the original sin originated, man, who is composed of body and soul, has to endure the impulse of his flesh that selfishly claims for the pleasure of sexuality, while at the same time ignoring the discipline with which God has ordered the ways of the human body. Purity is thus a virtue to be attained by the grace of God, as well as a particular personal struggle.
In order to be pure in heart it is necessary to firmly reject impure thoughts and desires, which are the internal root of sin against chastity, and are already sin when indulged. However, it is worth rejecting impurity, because purity is one of the greatest sources of joy, peace and energy in the development of the human being. As Jesus said during the Sermon at the mountain, “blessed are the pure in heart, for they shall see God” (Matthew 5:8).
From this invitation, we come to understand that purity hast a cost, but we know that it is also a great gift, a triumphal crown that we should crave for, and thereby defeating the mud of impurity, since impurity stains and is a bitter deception. It makes no sense to think that man is a beast unable to overcome his instincts; man is not a beast. And when God imposes the precept of purity from the same internal source, he does not order something impossible, but instead warns you to do what you can do, to ask for what you cannot, and He will help you to be capable, as the Council of Trent with St. Augustine taught.