in Form and Content in Didactic Poetry, ed Catherine Atherton, Bari 1998. Apologies for the poor copy.

I argue that there is nothing strange about the idea of writing philosophy in verse (as though the normal way to write it was in prose) for any philosopher up to and including Parmenides and Empedocles. Rather the reverse: the idea of writing philosophy as joined up arguments in prose is what is novel and needs explaining, if it even happened in any recognisable sense before Plato.  In a predominantly oral culture in which teaching is done by memorable declamation, verse is the default.
In addition it is a mistake to detach the content of a work of philosophy from its mode of presentation as though one might think the thoughts in prose and then "put them into poetry". Philosophers think their thoughts in the form that they can be expressed. The form of the poetry is part of the expression: it would be a mistake to think that there is a formless thought that is hidden under a fancy but unnecessary cloak of poetry.