  As should be clear from the above, there is no single and settled version of either the PC or the PSR, different thinkers employ them differently, and sometimes a single thinker employs them differently in different periods of their thought or in different texts and contexts. In what follows, we sketch one respectable interpretation of Wolff's use of these principles—together with notes on where he departs from Leibniz's (admittedly multi-faceted) use of the principles—at least in part because Wolff's approach does seem to be fairly close to Du Châtelet's own.