 By contrast, Susanna Goodin (1998) argues that ‘real essence’ and ‘internal constitution’ cannot be synonymous because, according to Locke, real essences are unknowable (IV.vi.5 &amp; 12), but internal constitutions are knowable (II.xxiii.12). One way to distinguish them is, as we saw above, to adopt the relativized view and interpret the real essence as the internal constitution that underlies the nominally essential properties, whereas the internal constitution of a substance is simply its physical make-up, independently of considerations of its nominal essence. So, on this view, Locke’s uses of ‘real essence’ and ‘internal constitution’ are non-synonymous technical terms.