(b) in the neutral schools of an anti-religious spirit the danger is the same, for the pupils must attend courses in which the interpretations given to history, science, philosophy, letters, etc., are unfriendly to the faith; (c) in the neutral schools whose spirit is not anti-religious, there is a danger of Indifferentism that arises from the system itself; for the very fact that religion is slighted tends to impress the students with the idea that it is unimportant or unrelated to other matters of life, and this prepares the way for doubt and scepticism. Moreover, since example teaches more effectively than the printed or spoken word, the neglect or contempt of religion by professors and fellow-pupils in mixed schools is a danger to faith. 869. The lawfulness or unlawfulness of attending or patronizing schools dangerous to faith must be decided according to the principles given above on the occasions of sin (see 263 sqq.). (a) If the danger to faith is voluntary, the use of such schools is not lawful, for those who are able are bound to seek or provide religious education both in elementary and higher schooling (see Canon 1373). Example: In the town of X there are good parochial and Catholic high schools. Sempronius could easily send his children to these schools, but he thinks that certain select schools offer greater social and financial advantages, and so he chooses them. His conduct is not lawful. (b) If the danger to faith is necessary, the use of such schools is lawful, provided the needed precautions are duly observed. Example: In the country district of Y there is no school except the public school, and therefore Balbus sends his children to that school. His conduct is lawful, but he must see that his children receive religious instruction outside of school. 870. The danger to faith is necessary when there is no Catholic school, or none that is sufficient for the needs of individual students, and their parents are unable to send them elsewhere. In such a case it is lawful to attend a school that is neutral, but means must be used to make the proximate danger remote. Such means are the following: (a) religious instruction must be taken outside of school, as in special week-day classes, Sunday school, home study, etc.; (b) special attention must be given to the strengthening of faith on those points that are attacked or slighted in the neutral school; (c) parents, guardians, or others responsible must see that the reading and the associates of their wards in the neutral schools are good, and that they are faithful to their religious duties. 871. Is attendance at non-Catholic schools sometimes unlawful, even when there are serious reasons in its favor?