851. There are two cases in which the use of writings forbidden by the Church is only a venial sin. (a) When a writing, which in itself is not dangerous or only slightly dangerous, is forbidden, not on account of its contents, but only on account of its lack of ecclesiastical approval, it is not ordinarily regarded as forbidden under grave sin (e.g., Catholic Translations of scripture that have not received the Imprimatur). (b) When a writing has been condemned on account of its contents or manner of presentation, one does not sin mortally, if the use one makes of it is only slight. 852. What constitutes notable use of forbidden matter is not determined by law, but recent moralists, bearing in mind the character of the law and what would prove proximately dangerous to faith for the generality today, offer the following rules: (a) notable matter in reading a book is three or four pages from the more dangerous parts, from thirty to sixty pages from the slightly dangerous parts; (b) notable matter in reading a paper or periodical is habitual use of it, or even one very bitter article; (c) notable matter in retention of forbidden writings is a period in excess of the reasonable time (say, a month) for securing permission or for delivering the writings to those who have a right to have them. 853. It is more difficult to decide what is notable matter, when a book has been condemned on account of its general tendency. (a) Under the natural law, of course, even a page or less is notable matter, if it places an individual in proximate danger; (b) under the positive law, perhaps anything in excess of one-tenth of the book would place one in proximate danger. But, as we are dealing now with the general tendency of a writing, this may have its effect on the reader before he has read one-tenth, if the book is large, or the treatment is very seductive. Hence, “one-tenth” is an approximation, rather than a rule.