The essential challenge posed by all texts is how to read the bias. Patterns of power and the organisation of social relationships were central concerns when Farnham Rehfisch studied in the early 1950s. By the time David Zeitlyn began his studies in the 1980s the role of language and religion had gained far greater prominence. Rehfisch hardly mentions religion in his thesis although there is quite a lot of relevant data in his field notes. One of the advantages about the Mambila is that the quantity of documentation is relatively small making it possible to present a fairly comprehensive collection. So the colonial reports formed some of the context for Farnham Rehfisch, whose work provides a context for Zeitlyn's research.