261. It is lawful to expose oneself to the danger of sin, if this can be done according to the laws of prudence, for otherwise absurdities would follow (e.g., that urgent duties should not be performed, if one feared they contained the danger of sin). The requirements of prudence referred to are: (a) that the one who exposes himself to the danger of sin be sure that his motive is good (viz., that he firmly intends to avoid the sin to which he may be tempted and to accomplish only the good he desires); (b) that the action he performs and which involves the danger is necessary, and bears a correspondence in importance to the gravity of the sin and the proximity of the risk; (c) that means be employed (e.g., prayer, pious thoughts, spiritual reading, and the use of the Sacraments), which will so reduce the danger that one has confident assurance that the danger will be encountered safely. 262. It is lawful to expose oneself to the possibility of sin, for, since almost every action may be perverted, one who wished to avoid the possibility of sin would have to leave this world and become confirmed in grace. 263. The Occasions of Sin are external circumstances--persons, places or things--which tempt one to sin. Examples: Persons who invite others to defraud and show how it can be accomplished, theatres where irreligious plays are staged, books that aim to depreciate virtue, etc. 264. The occasions of sin are of various kinds. (a) They are proximate or remote, according as it is morally certain, or only likely that they will lead to sin. (b) Occasions are necessary or free, according as one is able or not able to abandon them without difficulty. For example, one who chooses dishonest persons as his associates is in a free occasion of sin; one who is imprisoned with criminals is in a necessary occasion of sin. An occasion of sin is also necessary when the impossibility of leaving it is not physical, but moral. Examples: A wife who is bound to a provoking husband; a person who cannot give up an employment that offers many temptations, without suffering great temporal or spiritual injury, or without incurring a worse condition. (c) Occasions are present or absent, according as one has the occasion with him or must go to seek it. Examples; Intoxicants kept in his home are a present occasion of sin for a drunkard; atheistic lectures are an absent occasion of sin for one who has to go out to hear them. 265. It is not lawful to remain in a free occasion of sin,, whether it be present or absent; for to do so is to expose oneself rashly to the danger of sin (see 258 sqq.).