Thoughts of this latter kind are: (a) those in which one takes delight in an external act of sin being committed, as when one destroys one’s neighbor’s property with great internal satisfaction; here the thought forms one sin with the outer act; (b) those in which one delights in the mental image, not as it represents something morally wrong, but as it contains some object of lawful delight. There is a distinction between bad thoughts and thoughts on things that are bad. Examples: A moralist may think with pleasure about theft, not because he approves of it, but because it is a subject he has to know. A person may read detective stories with great interest, not because crime appeals to him, but because the style of the author is good, the details of the plot exciting, the manner of the crime mysterious, etc. There is danger in thoughts of this kind, however, if one indulges in them from mere curiosity, or immoderately, or if sin itself may take an attraction through them. 235. The gravity and species of pleasurable dwelling on inordinate thoughts vary according to the thing thought on (see on Objects, etc., 70 sqq.). (a) If pleasure is taken only in the object represented, the sin has the moral character of that object. Example: He who delights at the thought of theft, is guilty of theft; and if he thinks of a great theft, he is guilty of mortal sin. (b) If pleasure is also taken in the circumstances imaged in the mind, the sin takes on the added malice contained in the circumstances. Example: He who delights over the thought of the robbery of a church, is guilty of mental theft and sacrilege. 236. The following are signs that delight taken in a thought about sinful things is about their sinfulness, and not about some other of their properties: (a) if one thinks about them without any lawful necessity (such as that of study), but through mere curiosity, or without any good reason; (b) if at the same time one loves to think on them frequently and lingeringly, or shown great satisfaction whenever they are mentioned. Example: One who thinks about injustices for pastime and admires them as great exploits, who idolizes criminals as heroes or martyrs. 237. Sinful joy is an act of the will by which one takes delight in sins already committed by oneself or by others. We must distinguish between sinful joy and joy about things that are sinful. (a) Sinful joy rejoices over the iniquity contained in past acts, either because it loves that iniquity in itself, or because it loves it as the cause of some gain. Examples: An unjust and revengeful man rejoices when he thinks of the oppression he exercised against some helpless person who had incurred his wrath. A criminal recalls with joy the perjuries by which his helpers secured his escape from justice.