Plato denigrated poets, claiming that they did not understand what they were saying.
Quite simply, he did not understand the creative process.
In the creative process, the person uses the intuitive mind. Sometimes he rationally does not understand what he is saying. Making rational sense of it comes later. The work of the poet or the artist can frequently inform understanding that then leads to thought or discoveries. He may not immediately understand what is coming out; but eventually he does – and others do.
There are other times when it can work the other way around. In many situations, thought dictates art. There are many Christian hymns that are based on the Bible. There are many movies that express themes from psychology. There are many poems that express Enlightenment, or Romantic, or Victorian, thought.
The rational and the intuitive are both capable of leading and following. Sometimes someone stumbles onto discoveries through intuition. Sometimes someone takes themes that have been expressed rationally and turns them into art. Both the thinker and the poet can lead or follow. In the best scenario, one is both, and he both uses the intuitive to extend the rational and the rational to extend the intuitive.
Both the poet and the philosopher can come up with valuable communications. Either one can also base his craft upon that of the other. The intuitive and the rational are both capable of going into meaningful places. When one has the use of both, one has two methods working for him rather than merely one. And then one can arrive at all sorts of valuable contributions in all sorts of subjects.