A reason to preserve the physical book that has been digitized is that it is the authentic and original version that can be used as a reference in the future. If there is ever a controversy about the digital version, the original can be examined. A seed bank such as the Svalbard Global Seed Vault is seen as an authoritative and safe version of crops we are growing. Saving physical copies of digitized books might at least be seen in a similar light as an authoritative and safe copy that may be called upon in the future.They are therefore creating a facility that can accomodate up to ten million items in long term storage.
As the Internet Archive has digitized collections and placed them on our computer disks, we have found that the digital versions have more and more in common with physical versions. The computer hard disks, while holding digital data, are still physical objects. As such we archive them as they retire after their 3-5 year lifetime. Similarly, we also archive microfilm, which was a previous generation’s access format. So hard drives are just another physical format that stores information. This connection showed us that physical archiving is still an important function in a digital era.
Working with donors of books has been rewarding because an alternative for many of these books was the used book market or being destroyed. We have found everyone involved has a visceral repulsion to destroying books.