Book II, Part 1, Chapter 10. Of venial Sins

1. Though these be the chief sins you are carefully to avoid, yet do not think you are, therefore, allowed to run freely into all venial sins. On the contrary, I earnestly entreat you, not to be one of those who make no scruple of committing a sin when once they know it is not mortal. Consider what the wise man says*. " He that despises small things, will fall by degrees into greater ;" Eccl. xix. 1. Think of the old proverb, For want of a nail we lose a shoe ; for want of a shoe we lose a horse, and for want of a horse a trooper. Houses that fall with age begin their decay with some little flaw, which by degrees grows bigger, till the whole building comes to the ground. Consider that though in reality neither seven thousand venial sins, nor seven thousand to those, can make up one mortal, yet that which St. Augustine says is true, viz. " Do not despise venial sins, because they are but little ; but be afraid of committing them because they are many : we often see, that little animals may kill a man, when there is a great number of them : is not a grain of sand a very small thing ? and yet if you overload a vessel with it, it will certainly sink. How small are drops of water ! yet they make the greatest rivers, and bear down the most stately edifices in the world." Super Joan. Trac. 12. ad fin. Tom. 9. et L. de decern chordis, c. 11. et L. de Medicina. Poenitentium ad fin. Tom. 9. c. 2. The meaning of this sentence of St. Augustine is, not that many venial amount to a mortal sin, but that they dispose the soul to mortal sin, and very often make a man fall into it. Nor is this only true, but that also which St. Gregory says, " That to fall into small sins is sometimes more dangerous than to fall into great ones ;" In Pastora, p. 3. c. 33. Because the greater a fault is, the more it discovers itself, and is, by consequence, the more easy to be remedied ; whereas little faults, being looked upon as nothing, the more securely a man commits them, the greater danger he is in of falling frequently into the same again.

2. In fine, venial sins, though ever so little, are very prejudicial to the soul, because they take away devotion, disturb the peace and quiet of conscience, extinguish the heat of charity, weaken the heart, destroy the vigor of the soul, impair the strength of the spiritual life, and, in short, resist in some manner the Holy Ghost, himself, and hinder his operations in us. For this reason we are obliged to use the utmost diligence for avoiding of these sins, since it is certain there is no enemy, how mean soever, but may be able to do us much harm, if we do not secure ourselves against him.

3. Now, if you would know wherein these sins particularly consist ; I answer, that, in a little anger, gluttony or vanity, in idle words and thoughts, in immoderate laughing and jesting, in the loss of time, in sleeping too much, in lies and flatteries, and the like.

4. We have here described three sorts of sins ; one which is generally mortal, another that is commonly venial, and a third that lies, as it were, between these two extremes ; so that they are sometimes mortal, and sometimes only venial. It is requisite we shun all these in general, much more than those which are in the middle, and most of all those that are mortal ; because by those alone our peace with God is disturbed, our friendship violated, and by the same we lose all the goods of grace, and all the infused virtues ; though faith and hope, it is true, cannot be lost but by the contrary acts.