The ‘poetry’ of my title has at least the virtue of brevity as a description of the sort of literature Plato discusses in Books 2, 3, and 10 of the Republic. But in its Platonic sense ‘poetry’ is too narrow a description. Two characteristics recognized by Plato as invariably belonging to poetry (poiēsis) are (i) that what it composes are fictional stories (muthoi) (Phd. 61 b), and (ii) that it composes them in verse (Grg. 502 c; Smp. 205 c; R. 393 d, 601 d, 607 d; Phdr. 258 d). And the sort of literature discussed in the Republic, while it invariably has characteristic (i), does not invariably have (ii).
1 Substantially a paper read at the A.G.M. of the Classical Association at the University College of Wales, Aberystwyth in April 1976.