'erets,' 'ratsah,' and imaginative etymological rabbinic interpretation

From James Barr:

Why, for instance, Genesis Rabba asks with reference to Gen. 1:10, did God call the dry land ארץ ['erets]? The answer is: because [it] "conformed" (רצח [ratsah]) to his "will" (רצון [ratsohn]. Etymologizing interpretation of this kind, though found particularly in connexion with personal names, is to be found in all sorts of other connexions also [in rabbinic literature].

- James Barr, Comparative Philology and the Text of the Old Testament, p.45