Sometimes we are moved towards one part of a contradiction by nothing more than a kind of regard or esteem resulting from the way something represented. This is analogous to the way in which a particular food appears disgusting when it is represented in the image of something disgusting. The art of poetry is ordered to this. For the poet's vocation is to guide us towards what is virtuous by representing it as attractive.
Thomas Aquinas, Commentary on Aristotle's Posterior Analytics, Berquist, tr., Dumb Ox (Notre Dame: 2007), p. 3. What Aquinas means by 'some part of a contradiction' here is one of two mutually exclusive alternatives; and 'art of poetry' would be better translated more literally as 'poetics', which in medieval Aristotelianism (both Muslim and Christian) is one of the departments of logic (due to the fact that Aristotle's Rhetoric and Poetics were interpreted as dealing with special kinds of inference or reasoning). 'Vocation' is not in the original. The Latin is:
Quandoque vero sola existimatio declinat in aliquam partem contradictionis propter aliquam repraesentationem, ad modum quo fit homini abominatio alicuius cibi, si repraesentetur ei sub similitudine alicuius abominabilis. Et ad hoc ordinatur poetica; nam poetae est inducere ad aliquod virtuosum per aliquam decentem repraesentationem.