Authenticity is a difficult and taxing notion in both the digital and the analogue world. It is a retrospective and by implication dynamic notion, a reaction to whether or not we are dealing with the genuine article, that an object is what it purports to be at a moment in time and its content can be validated using available technology. It is not an end in itself like a fresh herring, but a red herring which, because of the pungent smell of the smokehouse, can put the hounds off the scent. Moreover it is not an absolute: an object that might appear perfectly authentic from one perspective may be considered to lack sufficient tokens of authenticity in another, and may later from both viewpoints be considered invalid. Content change may be captured in technologies, but does it necessarily follow that the intellectual content remains the same? Revolutions in technology may change the 'container' (for example a card catalogue becomes a database), but how do such migrations affect content and the procedures and practices that surround it? Is entering entities in a database the same as filling in cards? Distribution channels have always influenced structure and form without necessarily changing intellectual content or associated practice. In addressing such issues we warn against the ever present danger of a collapse into technological determinism with an accompanying utopian optimism [P. Flichy, The Internet Imaginaire, MIT Press, Cambridge, MA, 2007, Liz Carrey-Libbrecht. (trans.)]. We propose that discussion of identity needs to shift away from discussion of technologies for preserving information towards characterisation of the persistent intellectual content. In the migration to the digital we are especially concerned with four separate but related issues of identity from this perspective:• functionally identical replicas • superficially identical replicas • similar objects • earlier/later versions We conclude that identity is not a technical issue: notions of identity, like authenticity, are dynamic and have to deal with the non-transitive relations in stages of documents and objects. We are convinced that only by adopting such a stance can any progress be made in the sterile debate about digital preservation which logically must be downstream from the resolution of notions of authenticity that themselves are reactive to issues of intellectual content and available technology that following Aristotle we characterise as techné.