text:  Naturally when once a roll of parchment or of vellum had done its office by propagating through a series of generations what once had possessed an interest for _them_ but which under changes of opinion or of taste had faded to their feelings or had become obsolete for their understandings the whole _membrana_ or vellum skin the twofold product of human skill costly material and costly freight of thought which it carried drooped in value concurrently--supposing that each were inalienably associated to the other