What makes the expert, and his expertise?

Medicine and law were territories lorded over by highly specialized experts, and seemingly ought to have been highly pragmatic. But were they? How, we might ask, was specialized expertise altogether construed in the Roman context? And how was a figure of authority (an expert) in an area of specialization marked out as such? How was his proficiency to be demonstrated? And are we talking of a stature for such people that is in any way, or ways, similar to modern professionalism? Instead of attempting to offer a comprehensive overview of specialized expertise, and its pragmatic effects, in the Roman world, the present chapter is structured around some particular texts, which can provide illustrative case studies, namely Vitruvius’ De architectura, Frontinus’ De aquis, Pliny’s Epistulae, and Balbus and the Corpus Agrimensorum.