At this stage, we can introduce a further central innovation in the analysis of power that Foucault proposes, namely, what he calls "power-knowledge relations. The basic thought is again a simple one: the ways in which power is exercised are structured by the field of knowledge within which the exercise of power takes place and, in turn, this exercise of power provides material for this field of knowledge. Returning to our piano player, we can note that the child's practice is situated in a field of knowledge in which pedagogics inform, for example, the appropriate arrangement of the body in relation to the instrument, the selection of suitable pieces for beginning, intermediate, and advanced students; guidance on how much practice is required for a normal rate of progression in proficiency-and much else besides.