The 9th and 10th commandments teach moral principles concerning THOUGHTS and DESIRES. While the 6th commandment covers actions concerning purity, the 9th covers thoughts and desires about the same virtue. The 7th commandment covers actions regarding wise use of material things, the 10th deals with thoughts and desires concerning the same.
1.1 "For where your treasure is, there will your heart be also." (Matthew 6:21)
Every man longs for happiness. This desire is built into each one. Saint Thomas, quoting Saint Augustine in the Summa Theologiae (I-IIae q1 a7) says:
Augustine says (De Trinitate xiii, 3) that all men agree in desiring the last end, which is happiness.
Point 533 of the Compendium of the Catechism of the Catholic Church (cf CCC 2548-2550, 2557) says:
The greatest desire of the human person is to see God. “I want to see God” is the cry of our whole being. We realize our true and full happiness in the vision and beatitude of the One who created us out of love and draws us to himself with infinite love.
However, because of original sin, our perception of what things can make us happy has been blurred. Quite often, we mistakenly think that some created thing (POWER, PLEASURE, or POSSESSIONS) can make us happy and contented. So we start placing our hearts on them. We put them on a pedestal. We give them a lot of attention. These three--power, pleasure, or possessions--are actually good in themselves, as long as they are used according to God's plan. By creating us in His image and likeness, God has given us the power to manage these (see point 6 of Lesson 6).
But original sin has clouded our mind and perverted our will, leading us to use our God-given abilities without any regard for God's plan. Saint John explains the triple temptation that confronts us.
Do not love the world or the things in the world. If any one loves the world, love for the Father is not in him. 16 For all that is in the world, the LUST OF THE FLESH and the LUST OF THE EYES and the PRIDE OF LIFE, is not of the Father but is of the world. 17 And the world passes away, and the lust of it; but he who does the will of God abides for ever. (I John 2:15-17)
However, it is possible to counter the effects of our weakness through the practice of VIRTUE. Moreover, God's infinite love has given us a way to remedy this TRIPLE CONCUPISCENCE through the virtues and gifts of the Holy Spirit.
Power, pleasure and possessions are fleeting--here today, gone tomorrow. This is why God does not want us to place our hearts on them as they spell certain disappointment and frustration at the end of our life. The 9th commandment helps keep our heart away from pleasure; the 10th from power or possessions. The words of Jesus in Luke 12:16-34 are most reassuring:
16 And he told them a parable, saying, "The land of a rich man brought forth plentifully; 17 and he thought to himself, 'What shall I do, for I have nowhere to store my crops?' 18 And he said, 'I will do this: I will pull down my barns, and build larger ones; and there I will store all my grain and my goods. 19 And I will say to my soul, Soul, you have ample goods laid up for many years; take your ease, eat, drink, be merry.' 20 But God said to him, 'Fool! This night your soul is required of you; and the things you have prepared, whose will they be?' 21 So is he who lays up treasure for himself, and is not rich toward God."
22 And he said to his disciples, "Therefore I tell you, do not be anxious about your life, what you shall eat, nor about your body, what you shall put on. 23 For life is more than food, and the body more than clothing. 24 Consider the ravens: they neither sow nor reap, they have neither storehouse nor barn, and yet God feeds them. Of how much more value are you than the birds! 25 And which of you by being anxious can add a cubit to his span of life? 26 If then you are not able to do as small a thing as that, why are you anxious about the rest? 27 Consider the lilies, how they grow; they neither toil nor spin; yet I tell you, even Solomon in all his glory was not arrayed like one of these. 28 But if God so clothes the grass which is alive in the field today and tomorrow is thrown into the oven, how much more will he clothe you, O men of little faith!
29 And do not seek what you are to eat and what you are to drink, nor be of anxious mind. 30 For all the nations of the world seek these things; and your Father knows that you need them. 31 Instead, seek his kingdom, and these things shall be yours as well.
32 "Fear not, little flock, for it is your Father's good pleasure to give you the kingdom. 33 Sell your possessions, and give alms; provide yourselves with purses that do not grow old, with a treasure in the heavens that does not fail, where no thief approaches and no moth destroys. 34 For where your treasure is, there will your heart be also.
On the other hand, what God asks us is to put our hearts on Him, not because He needs us, but because we need Him. He alone is infinite Truth, Goodness, and Beauty. No created thing can ever match what God offers. The infinite happiness we seek can only be found in Him. This is what the Psalms remind us of.
O God, thou art my God, I seek thee, my soul thirsts for thee; my flesh faints for thee, as in a dry and weary land where no water is. (Psalm 63:1)
1 As a hart longs for flowing streams, so longs my soul for thee, O God. 2 My soul thirsts for God, for the living God. When shall I come and behold the face of God? (Psalm 42:1-2)
1 How long, O LORD? Wilt thou forget me for ever? How long wilt thou hide thy face from me? 2 How long must I bear pain in my soul, and have sorrow in my heart all the day? How long shall my enemy be exalted over me? (Psalm 13:1-2)
This is why God tells Israel in chapter 6 of the book of Deuteronomy:
4 "Hear, O Israel: The LORD our God is one LORD; 5 and you shall love the LORD your God with all your heart, and with all your soul, and with all your might. 6 And these words which I command you this day shall be upon your heart; 7 and you shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. 8 And you shall bind them as a sign upon your hand, and they shall be as frontlets between your eyes. 9 And you shall write them on the doorposts of your house and on your gates."
The book of Proverbs (23:25) thus says:
26 My son, give me your heart, and let your eyes observe my ways.
1.2 Purification of the Heart
Why the heart? The Catechism of the Catholic Church (2517) says:
The heart is the seat of moral personality: "Out of the heart come evil thoughts, murder, adultery, fornication..." [Matthew 15:19]. The struggle against carnal covetousness entails purifying the heart and practicing temperance:
Remain simple and innocent, and you will be like little children who do not know the evil that destroys man's life [Pastor Hermae, Mandate 2, 1: PG 2, 916].
Saint Josemaría Escrivá used to say that the battles of the spiritual life are won and lost in the heart. The heart is the battleground between good and evil. And we most often neglect it because we underestimate its importance.
Points 2518 and 2519 of the CCC explains what purity of heart means.
The sixth beatitude proclaims, "Blessed are the pure in heart, for they shall see God" [Matthew 5:8]. "Pure in heart" refers to those who have attuned their intellects and wills to the demands of God's holiness, chiefly in three areas: CHARITY [cf I Timothy 4:3-9; II Timothy 2:22]; CHASTITY or SEXUAL RECTITUDE [cf I Thessalonians 4:7; Colossians 3:5; Ephesians 4:19]; love of truth and orthodoxy of faith [cf Titus 1:15; I Timothy 1:3-4; II Timothy 2:23-26]. There is a connection between purity of heart, of body, and of faith:
The faithful must believe the articles of the Creed "so that by believing they may obey God, by obeying may live well, by living well may purify their hearts, and with pure hearts may understand what they believe" [St Augustine, De fide et symbolo 10, 25: PL 40, 196].
The "pure in heart" are promised that they will see God face to face and be like him [cf I Corinthians 13:12; I John 3:2]. Purity of heart is the precondition of the vision of God. Even now it enables us to see according to God, to accept others as "neighbours"; it lets us perceive the human body--ours and our neighbour's--as a temple of the Holy Spirit, a manifestation of divine beauty.
How does one reach purity of heart? In this battle, we need to remember two things: [1] DIVINE GRACE and [2] HUMAN COOPERATION THROUGH STRUGGLE. Let us discuss the latter first.
[1] HUMAN EFFORT AND COOPERATION WITH GRACE. The CCCC (529; cf CCC 2520) says:
In the battle against disordered desires the baptised person is able, by the grace of God, to achieve purity of heart through the virtue and gift of chastity, through purity of intention, purity of vision (both exterior and interior), discipline of the imagination and of feelings and by prayer.
Aside from prayer, DISCIPLINE, i.e. MORTIFICATION, should never be neglected. Without it, a person is like an athlete who shows up in a contest without having undergone any practise sessions or training. He is like a soldier who goes to battle unprepared. Saint Josemaría writes in The Way (307)
That supernatural mode of conduct is a truly military tactic.
You carry on the war — the daily struggles of your interior — far from the main walls of your fortress.
And the enemy meets you there: in your small mortifications, your customary prayer, your methodical work, your plan of life: and with difficulty will he come close to the easily-scaled battlements of your castle. And if he does come, he comes exhausted.
Holy purity also calls for MODESTY and an effort to PURIFY THE SOCIAL CLIMATE. With regard to the latter, we should remember that concerns about the environment--ecology--must include man, not only what benefits his body, but above all what benefits his soul. We should struggle to rid the world not only of material pollutants, but spiritual debris as well. The CCCC (530; cf CCC 2521-2527, 2533) says:
Purity requires MODESTY which, while protecting the intimate centre of the person, expresses the sensitivity of chastity. It guides how one looks at others and behaves toward them in conformity with the dignity of persons and their communion. Purity frees one from wide-spread eroticism and avoids those things which foster morbid curiosity. Purity also requires a PURIFICATION OF THE SOCIAL CLIMATE by means of a constant struggle against moral permissiveness which is founded on an erroneous conception of human freedom.
[2] DIVINE GRACE. Moreover, one should not forget that the battles of the spiritual life cannot be fought with human weapons or tactics alone. Indeed, we could not do a single thing without God's grace; without Him we could do absolutely nothing (cf John 15:5). Thus, Saint Paul says in his Letter to the Ephesians (6:11-19):
11 Put on the WHOLE ARMOUR OF GOD, that you may be able to stand against the wiles of the devil. 12 For we are not contending against flesh and blood, but against the principalities, against the powers, against the world rulers of this present darkness, against the spiritual hosts of wickedness in the heavenly places. 13 Therefore take the whole armour of God, that you may be able to withstand in the evil day, and having done all, to stand. 14 Stand therefore, having girded your loins with truth, and having put on the breastplate of righteousness, 15 and having shod your feet with the equipment of the gospel of peace; 16 besides all these, taking the shield of faith, with which you can quench all the flaming darts of the evil one. 17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God. 18 Pray at all times in the Spirit, with all prayer and supplication. To that end keep alert with all perseverance, making supplication for all the saints, 19 and also for me ...
God's strength is made available to us above all through the SACRAMENTS, particularly the Sacrament of Penance and of the Holy Eucharist. A person who wants to live purity of heart must try WEEKLY CONFESSION and DAILY MASS. If we really want to win our spiritual battles, we need to have the humility to beg and plead for grace through prayer and the sacraments. It is also advisable to seek spiritual direction so that one enters the contest with a clear game plan, a realistic strategy. Saint Paul says in his First Letter to the Corinthians (9:26):
26 Well, I do not run aimlessly, I do not box as one beating the air...
1.3 Poverty of spirit
What does Jesus call for in poverty of spirit? Point 532 of the CCCC (cf CCC 2544-2547, 2556) explains:
Jesus calls his disciples to prefer him to everything and everyone. Detachment from riches--in the spirit of evangelical poverty--and self-abandonment to divine providence free us from anxiety about the future and prepare us for the blessedness of the "poor in spirit, for theirs is the kingdom of heaven" (Matthew 5:3).
Sins committed in one's heart--internal sins--may seem harmless, because they may have no outward expression. But we have already said earlier that the battles of spiritual life are won or lost in the heart. In fact, internal sins can be more dangerous than external sins for at least three reasons: they [1] are more EASILY COMMITTED and EASILY CONCEALED, [2] are more DIFFICULT TO AVOID, and [3] RECEIVE LESS ATTENTION.
There are three kinds of internal sins: [1] DELIBERATE PLEASURE (delectatio morosa), [2] SINFUL JOY (gaudium peccaminosum), and [3] EVIL DESIRE (desiderium pravum).
2.1 Deliberate pleasure
DELIBERATE PLEASURE. Also called "bad thoughts" or "imaginations". This is to take pleasure in an evil object in the imagination which is not accompanied by a desire for the object. The Latin adjective morosa, "lingering," does not refer to the duration of the pleasure, but to the voluntary delay in rejecting the sinful representation. It means entertaining the thought.
If the evil object is a mortal sin, then the deliberate pleasure is also mortal. In confession, however, there is often no need to go into specifics; it may be enough to say that one consented to bad thoughts against charity, or chastity.
2.2 Sinful joy
Sinful joy is complacency (that is, take pleasure) in some evil action really performed by oneself or by others (that is wilfully recalling sinful actions). It is much more serious than deliberate pleasure, since it implies approving an actual sin. In other respects, the same considerations can be applied to both.
Nevertheless, it is licit to rejoice in the good that may have resulted from a bad action. Thus, one may rejoice in the triumph of a martyr, even if it is a consequence of the bad action of the persecutor; but one cannot rejoice in the evil act itself.
2.3 Evil desire
EVIL DESIRE is taking pleasure in an evil act one intends to do. This desire can either be effective or absolute, or ineffective.
As we have said above, we need to be wary about internal sins. A person who refuses to take notice of his internal sins will easily deform his conscience. A soul who gives in to internal sins such as critical judgements, unkind thoughts, reactions of pride, sensuality, envy, or vanity and does little to uproot them would eventually refuse to acknowledge that these internal sins are the cause of his external reactions of self-centredness, touchiness, disproportionate fits of anger, indifference to the others, or lack of spirit of sacrifice. This path may even lead to serious sins, which the person may not admit because of a habitual lack of sincerity.
(See Lesson 30 for discussion on the seven capital sins.)