How should I take the concept of 'identical being'?

In this following context, how should I take the concepts of 'identical being' and 'identity in process'? Can the concept 'identical being' have 'unchanging entity'? Would you give any idea about this bold and italic sentence? I'm confused about these usages. Context: > Every fresh consciousness consists of the potentialities of its > predecessors together with something more. There is, therefore, a > continuous flow of consciousness like a stream without any > interruption. The subsequent thought-moment is neither absolutely the > same as its predecessor since that which goes to make it up is not > identical—nor entirely another—being the same continuity of Kamma > energy. Here ***there is no identical being but there is an identity > in process.*** Source: P. 61 Buddhism in a Nutshell by Narada Thera