Into how many parts do you divide the theory of rhetoric?

I'm dipping into Cicero's "de partitione oratoria" ("The Classification of Oratory") at the moment (Rackham's translation in the Loeb Classical Library).

He says that the theory of rhetoric ("doctrina dicendi", lit. "the teaching of speaking") should be divided into three parts (de partione oratoria 3):

• The speaker's personal resources (lit. "strength") ("vis oratoris").
• The speech ("oratio").
• The question ("quaestio").