In this book Schein make his point regarding two very different roles, that, in practice, very often become merged and mixed: the role of the ethnographer as an "invisible" recorder of the nature of a given culture or organization, where he is expected to be unobtrusive and not affecting the daily activities in the place studied.
At the other hand, the clinical perspective, stemming from action research, is a very different role: the clinician is not impartial nor uninvolved. The clinician is usually a consultant brought in specifically to effect change in an organization, but in order to change it he needs to gain trust of members of that organization, and most of all, be helpful.