> Oddly enough - the process in a library for digitising a copy of a book can be fairly destructive, as far as I understood from those doing it (at CUDL). The spine is chopped off, to make it easier to put it into a machine for scanning all the pages.
The general consensus among modern librarians came around on that subject, and now this kind of destructive processes is rare and generally frowned upon. A librarian friend once explained to me there was always two "schools" among librarians:
1. Those who only value the content of books. For those, copying/digitalizing a rare book is all that is needed in order to preserve said book.
2. Those who also value the physical object of the book as a historical artifact. For those keeping rare books in good condition is also necessary for preservation.
In the middle 1900s with the mass adoption of the microfilm, the first school gained the upper hand, and many libraries conducted mass projects of microfilming and destroying historical archives. Those were mostly motivated by a false belief that books were super fragile and wouldn't last anyway (I mean, if you believe the book will fall apart on its own, then you would be less reticent about using destructive methods to make the best copy possible).
In the last few decades the tides changed, librarians realized that books are not that fragile, and can be kept pretty much indefinitely if closed and protected from humidity (and fire). Also they realized that microfilm is crap, and that copying/digitizing is a error prone process, so a lot of stuff was lost because someone skipped a page, or the film was damaged, and the original was destroyed. So the movement to keep originals grew in strength, being almost a consensus now a days, and modern digitizing processes/machines are specially designed to be gentle and non destructive.