Commentary Par I 4

Some commentators, perhaps beginning with Pietrobono (DDP Pietrobono.Par.I.4), put forward the notion that the reference is to all ten heavens, that is, to the totality of this super-terrestrial world.  A few have also argued that the reference is to the outermost of the physical heavenly spheres, either the Crystalline, or the Primum Mobile.  However, it seems utterly clear that Dante is referring to the Empyrean, God's 'home' (insofar as He who is everywhere can be thought of as located in a particular anywhere as well).  Scartazzini (DDP Scartazzini.Par.I.4) was perhaps the first to refer to the Epistle to Cangrande (which devotes considerable space to a literal exposition of this verse, Epist.XIII.66-76) as eventual justification of this reading: 'And it is called the Empyrean, which is as much as to say, the heaven glowing with fire or heat; not that there is material fire or heat therein, but spiritual, which is holy love, or charity' (XIII.68 -- tr. P. Toynbee).