Competing notions of what a Ph.D. has been, is and should be are undercurrents in doctoral education. A longitudinal study of Ph.D. supervision based on interviews and concept mapping was used to surface understandings of the purpose of a Ph.D. This research tracks change over time for both the student and the supervisor. The data were analysed using Bernstein's horizontal and vertical discourses, describing how students can focus on "content" knowledge aspects and miss out on key "process" understanding. A discussion follows on how the pedagogic discourse of supervision can work towards a balance of knowledge and understanding. (Contains 6 figures.)