This isn't copy protection, or even watermarking to identify who's "leaking the source".
Hand-copying text is error-prone, and copies are often made from copies, so there's the chance to reconstruct a "family tree" even after knowledge of what copied from what is lost.
Hand-copying text is error-prone, and copies are often made from copies, so there's the chance to reconstruct a "family tree" even after knowledge of what copied from what is lost.
See, for example, this: http://ahds.ac.uk/archaeology/creating/case-studies/canterbu...