472. It is held that a cleric who said the Breviary in the morning, just before he was ordained subdeacon and undertook the obligation of the Office, satisfied by that anticipated recitation; likewise, that a traveller who heard Mass in a place where a holyday of obligation of the general law was not in force, has satisfied by anticipation, if later in the morning he reaches as his destination a place where the holyday is observed. For in both these cases the law intends that the Office be said, or the Mass be heard within the day. 473. If a person who is now able to do what the law requires, foresees that he will not be able to do this when the time set by the law arrives, he is not obliged to anticipate fulfillment, even when he has the privilege of anticipation. Examples: A cleric who at 2 p.m. is able to anticipate Matins for tomorrow, and who knows that later, on account of an operation, he will not be able to say his Office, is not bound to anticipate; for no one is obliged to use a privilege. A person who is able to hear Mass on Saturday, and who knows that all of Sunday must be spent on the train, is not obliged to hear Mass on Saturday, though of course this is the better thing to do. 474. The internal acts concerned in the fulfillment of a law are: (a) those in the intellect, such as knowledge; (b) those in the will, such as consent, motive. 475. Knowledge of what one is doing is sometimes necessary, sometimes unnecessary for the fulfillment of a law. (a) If the law is prohibitive, knowledge is not necessary, since nothing more is required by the law than the omission of what is forbidden. Example: He who ate no meat on a day of abstinence has fulfilled the law, even though he was unconscious all day. (b) If the law is preceptive of a payment to be made, knowledge is not necessary, since the law requires nothing more than the effect of an external act. Example: He who pays his taxes while intoxicated fulfills his obligation, even though he does not know what he is doing. (c) If the law is preceptive of an act to be performed, knowledge is required, for it is supposed that the act will be exercised in a human manner. Example: He who sleeps all during Mass on Sunday does not fulfill his duty, for the law intends that one assist at Mass in a human way (i.e., with consciousness of what is being done). 476. Fulfillment of a law is not morally good and meritorious, unless it is voluntary (see 97 sqq.); but the legal obligation is sometimes satisfied even by an unwilling fulfillment. (a) When the law commands a payment to be made, one may will the contrary of what is commanded and yet fulfill one’s obligation. Example: He who pays his taxes unwillingly and under compulsion satisfies the law, which requires not an act, but its effect.