(b) In the second place, those “use” a forbidden writing who retain it--that is, who keep it in their home as belonging to themselves or borrowed from another, or who give it for safekeeping to another, even though they are not able to read it. Hence, a librarian who has forbidden books on his shelves does not break the law, since the books are not his property, nor are they kept in his home. A bookbinder also who receives forbidden books is considered as excused through _epieikeia_ for the time the books are in his shop, especially if his customer has the permission to read those books. Example: Sempronius bought an expensive work and then discovered that it is on the Index. Is he obliged to destroy it? No, if he does not wish to destroy it, he may, if he does not delay beyond a month, either give it to someone who has permission to keep it, or obtain that permission for himself. (c) In the third place, those “use” a forbidden writing who communicate it to others--for example, those who make presents of works that are on the Index, who lend such books to others, or place them where others will read them, who read to others passages or write out excerpts for them. It is lawful, however, for professors in theological and other classes of sacred science to read from forbidden works to their student body, if a suitable explanation and refutation exclude all danger. (d) Lastly, those fall under the law as violators who co-operate in the production or distribution of forbidden literature--for example, publishers, owners, authors, translators, booksellers, printers, etc. (cfr. 976 sqq., on cooperation in Worship). 863. The church law on forbidden literature affects all Catholics not excepted by law, no matter how learned they may be, what position they may hold, or how immune from danger they may seem, unless they obtain permission to read such literature from the Holy See, the Ordinary, or their regular Superior (Canon 1402). Those excepted by law and who do not need to seek such permission are certain prelates and students. (a) Cardinals, Bishops, and other Ordinaries (Canon 1401), and likewise major superiors in exempt clerical orders (Canon 198, Sec. 1) are not bound by the church prohibition of books dangerous to faith; (b) those who are pursuing theological or biblical studies may use forbidden editions of scripture, provided these are correct and complete as to the text, and contain no attacks on Catholic teaching in the introductions and annotations (Canon 1400). This permission extends not only to seminarians, but also to lay students; not only to those who are at school, but also to those who are really studying outside of school, such as professors, writers and those who are preparing lectures or dissertations.