Chapter 20 argued that Symbols, types recognized through rule or “convention” rather than inherent meaningfulness, not only emerge within co-operative action, but indeed are themselves forms of co-operative action. Focusing on the apprenticeship of young geologists in the field, two intertwined issues are investigated here. First, what forms of practice and sedimented skill make it possible for the nonnatural signs produced by one individual to be not only recognized, but also trusted by another? Second, how is an individual’s qualitative, sensory experience – haptic, visual, etc. – of the world being encountered transformed through public practice into the abstract types that animate and sustain the discourse and knowledge of the community? Co-operative practices regiment individual experience and perception within a public arena to create the sensorium, and the phenomenal world, of a profession. More simply, how are embodied knowledge, skill, and professional vision calibrated through systematic practice to create both the competent actors, and the public sensorium, that sustain a community’s distinctive ways of knowing, experiencing, and acting within the world that is the focus of its activities?

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