III. Many of the questions raised could be more easily settled in a personal interview than on paper.
Reply. The monk's vow being undertaken of his own will or wish cannot be given up without sin. For that which a man has vowed to God, he ought also to pay. Hence he who abandons his profession of a single life and betakes himself to military service or to marriage, must make atonement and clear himself publicly, because although such service may be innocent and the married state honourable, it is transgression to have forsaken the higher choice.
Question 15
Concerning young women who have worn the religious habit for some time but have not been dedicated, if they afterwards marry.
Reply. Young women, who without being forced by their parents' command but of their own free-will have taken the vow and habit of virginity, if afterwards they choose wedlock, act wrongly, even though they have not received dedication: of which they would doubtless not have been defrauded, if they had abided by their vow.
Question 16
Concerning those who have been left as infants by christian parents, if no proof of their baptism can be found whether they ought to be baptized?
Reply. If no proof exist among their kinsfolk and relations, nor among the clergy or neighbours whereby those, about whom the question is raised, may be proved to have been baptized, steps must be taken for their regeneration: lest they evidently perish; for in their case reason does not allow that what is not shown to have been done should seem to be repeated.
Question 17
Concerning those who have been captured by the enemy and are not aware whether they have been baptized but know they were several times taken to church by their parents, whether they can or ought to be baptized when they come back to Roman territory ?
Reply. Those who can remember that they used to go to church with their parents can remember whether they received what used to be given to their parents. But if this also has escaped their memory, it seems that that must be bestowed on them which is not known to have been bestowed because there can be no presumptuous rashness where the most loyal carefulness has been exercised.
Question 18
Concerning those who have come from Africa or Mauretania and know not in what sect they were baptized, what ought to be done in their case ?
Reply. These persons are not doubtful of their baptism, but profess ignorance as to the faith of those who baptized them: and hence since they have received the form of baptism in some way or other, they are not to be baptized but are to be united to the Catholics by imposition of hands, after the invocation of the Holy Spirit's power, which they could not receive from heretics.
Question 19
Concerning those who after being baptized in infancy were captured by the Gentiles, and lived with them after the manner of the Gentiles, when they come back to Roman territory as still young men, if they seek Communion, what shall be done?
Reply. If they have only lived with Gentiles and eaten sacrificial food, they can be purged by fasting and laying on of hands, in order that for the future abstaining from things offered to idols, they may be partakers of Christ's mysteries. But if they have either worshipped idols or been polluted with manslaughter or fornication, they must not be admitted to communion, except by public penance.
Source: Letters (New Advent)