contrary may conduce to it. The legislative authority may, for the public good and to further the end for which the society exists, prescribe or prohibit such acts according to circumstances. In itself it is indifferent on which side of the road a carriage is driven, and whether it passes another on the right or on the left; but where traffic is considerable it is necessary that these matters should be regulated by law or custom. To eat meat on Friday is in itself as lawful as to eat it on any other day, but the Church has forbidden it in order that her children may exercise themselves in the practice of temperance and mortification of the sensual appetite. When an indifferent act or one which already belongs to some special virtue is commanded by the legislator from a motive which belongs to some other virtue, the act commanded henceforth belongs to the virtue which furnished the motive, if the legislator so wills. And so, inasmuch as the j Church prescribes fasting Communion out of reverence for the Blessed Sacrament, one who receives not fasting is guilty of irreverence and sacrilege, though, apart from the Church's law, to receive Holy Communion not fasting would not be sinful. For just as an action may get a special moral quality from the end for which the agent performs it, so the motive of the legislator may give a distinct moral quality to an act which he commands. The same holds good of prohibitive laws.
5. Acts of heroic virtue which would be impossible for the body of the people cannot ordinarily be prescribed by law. A law must be morally possible of observance for the general body of the subjects. When, however, the public good requires acts of heroism, and especially when a state of life has been voluntarily assumed which demands heroism, acts of heroic virtue may then become matter of law. The soldier must obey orders at the risk of life, and the Church is justified in prescribing celibacy to all who freely choose to enter sacred orders. If anyone feels that he cannot observe the law, let him not volunteer for the service.
6. Merely internal acts which do not conduce to the common good of civil society, cannot be the subject-matter of civil law. The Church's end is the spiritual welfare of her children, to which internal acts contribute much; and so, many theologians hold that the Church may prescribe merely internal acts. She certainly has the power of prescribing internal actions concomitantly, as it is said, when they form part of a whole human action. Therefore, in commanding her children to hear Mass on Sundays, she bids them have the necessary
