(b) Culpable ignorance is not distinct from its effect (i.e., from a sin committed on account of the ignorance), if the truth one is ignorant of has to be known only on account of some passing duty that must be performed here and now; for in such a case the knowledge is required, not for its own sake, but for the sake of the duty. Hence, ignorance of fact or of a particular law is not distinct as a sin from the sin that results from it. Examples: Titus knows that he should not take money that belongs to another; but through his own carelessness he is ignorant of the fact that the money before him belongs to another, and takes the money. Balbus knows that the precept of the Church on fasting is obligatory; but through his own negligence he is unaware that today is a fast day, and does not fast. Titus and Balbus committed one sin apiece. (c) Culpable ignorance is distinct from its effect, if the truth one is ignorant of has to be known for its own sake; for in such a case one sins against the virtue of studiosity (see 905) by not knowing something which one should know habitually, and also against some other virtue by violating its precepts as a result of one’s sinful ignorance. Truths one is obliged to know for their own sake are the mysteries of faith, the Commandments of the Decalogue, the Precepts of the Church, and the duties of one’s own state. Examples: Sempronius through his own carelessness does not know the mystery of the Incarnation, and as a result blasphemes Christ. Titus does not know that stealing is a sin, and therefore he steals. In both cases two sins are committed, the sin of ignorance and the sin that resulted from ignorance. 908. Cases in which ignorance in matters of faith is not culpable are the following: (a) if one has used sufficient diligence to acquire knowledge, one is not responsible for one’s ignorance; (b) if one has not used sufficient diligence to acquire knowledge, one is not responsible for one’s ignorance, if the lack of diligence is not one’s fault. 909. Sufficient diligence is a broad term and has to be understood with relation to the mental ability of the person and the importance and difficulty of the truth in question. What is sufficient diligence in an illiterate person, or with regard to a matter of minor importance, would be insufficient in a learned person, or in a matter of greater importance. However, the following general rules can be given: (a) To be sufficient, diligence need not be as a rule supreme (i.e., it is not necessary that one employ every possible means to acquire instruction), for even the most conscientious persons feel they have used sufficient diligence when they have employed the usual means for obtaining religious instruction;