 It is all well and good speaking of a dynamics defined on relative configuration space, or shape space. However, it remains incumbent on our Machian theorists to construct explicit dynamics appropriate for these spaces: i.e., dynamics which do not recognise solutions related by the action of the similarity group (viz., translations, rotations, and dilatations) as being distinct. Given a dynamics on configuration space, one can indeed achieve this task. The procedure which implements this is known as ‘best matching’, and was developed in the seminal work of Barbour and Bertotti (1982), in which a version of Newtonian particle mechanics with dynamics formulated on relative configuration space was first constructed. The extension to shape space was undertaken in (Barbour 2003).