Does an imprimatur 'expire'?

[calian]

I don't know the proper term for this, but does a nihil obstat or imprimatur ever "expire"?

I have purchased a number of 19th-century Catholic books from estate auctions and antique stores. Most are prayer manuals, guides to popular devotions, and lives of the saints; most of that material is historical and fixed. But some are more theological, and some are catechisms. They were, of course, written before the changes in practice that came from Vatican II, before the current Catechism, and before the 20th-century revisions of the Code of Canon Law. However, most of them have a nihil obstat and imprimatur from the bishop at the time of publication.

I know that an imprimatur is no guarantee of infallability, and it's pretty obvious that when the book refers to the Austrian empire or somesuch that I have to translate that to modern political reality, so I do read with my common sense turned on. Guess what I'm asking is, what "weight" does a nihil obstat or imprimatur add to a book? Should it be ignored after a certain point? Does it just indicate that the work is doctrinally sound only at the time of publication? Since doctine does not change, are they "good" forever?

I know, this is probably a question for a lengthy treatise, and I'm expecting a one paragraph response. I appreciate any direction you can provide.

--Terry

[Michelle Arnold]

When a book is submitted to a diocese for the bishop's approval, it is first read by someone who has been delegated by the bishop for the task. This person reads the material. If it is without theological error, the nihil obstat is granted and the book is passed on to the bishop for approval. The bishop then grants an imprimatur, which is a notice that the diocese is granting its approval for the book to be printed. (Nihil obstat means "no problem" in Latin; imprimatur means "let it be printed.") If, on the other hand, the book does contain theological error, the reviewer will mark those places that need change; if the writer corrects the errors, the book can then receive the nihil obstat and imprimatur.

The nihil obstat and imprimatur only mean that the book is free of doctrinal error. It does not mean that it is free of non-doctrinal factual error or that the bishop or reviewer agrees with the opinions expressed in the manuscript. Doctrine is unchanging, so notices of freedom from doctrinal error do not "expire." The notices of doctrinal error are not infallible, however; they are only as reliable as are the doctrinal knowledge and orthodoxy of the person entrusted to grant the nihil obstat.

Another consideration to keep in mind is that while doctrine never changes, our understanding of doctrine does develop. For example, a nineteenth-century book would teach the doctrine of the Assumption with less dogmatic certitude than a book published after Pope Pius XII infallibly defined this Marian dogma in the twentieth century. Of course, disciplines, on the other hand, are changeable. A nineteenth-century book that stated that the liturgy of the Roman rite must be said in Latin alone would be absolutely correct for the time of its publication. After properly-constituted ecclesial authorities changed the discipline of saying the liturgy only in Latin, this disciplinary measure was no longer in effect.