 Relying largely on Spinoza's denial of the divisibility or measurability of extension as it is properly conceived (as opposed to imagined), Alison Peterman (Peterman 2012, 2015) has advanced the bold thesis that Spinoza's extension is not spatial or dimensional at all, and that, accordingly, Spinoza's bodies do not occupy space. On this view, Spinoza means something quite different by “extension” than Descartes or anyone else has meant. For Peterman, it is not just the apparent divisibility and measurability of extension that is an illusion of the imagination, but its very spatiality. Peterman argues that spatial extent would necessarily be, at least potentially, divisible, and that since Spinoza denies that extension is even potentially divisible, he must not understand extension as spatial (Peterman 2012,  p. 50).[18] She further supports this view by noting that, while Spinoza explicitly characterizes extension in spatial terms in his exposition of Descartes' view in the PCP, he does not so define extension in expounding his own views in the Ethics, but rather says that extension is “conceived through itself” .