Poetry is

In what sense and how far is the genius master of his madness?
For it goes without saying that to a certain degree he is master
of it, since otherwise he would be actually a madman. For such
observations, however, ingenuity in a high degree is requisite,
and love; for to make observation upon a superior mind is very difficult.
--Kierkegaard, Fear and Trembling

Madness in great ones must not unwatch\'d go.
--Shakespeare, Hamlet

Poetry is not inspiration. Poetry is neither reasonable, irrational, or a result of some sort of mania. Poetry is language through which the writer affects and as a result the reader is affected. Within this, one finds a cause and effect relationship. Plato, in Ion, refers to the poet as, "a light and winged and holy thing, and there is no invention in him until he has been inspired and is out of this senses, and reason is longer in him". In contrast, Aristotle contends that, "poetry implies either a happy gift of nature or a strain of madness. In one case a man can take the mould of any character; in the other, he is lifted out of his proper self" (Poetics, XVII. 2). Longinus adds that, "Truly beautiful words are the very light of thought" (On The Sublime, XXX. 63), and "literary composition...sets in motion manifold ideas of words, thoughts, actions, beauty, and melody, all of them produced and nourished within us...the emotion of the speaker is introduced into the spirits of those who listen and...at once charm us and dispose us for the majestic...But it appears madness to raise a question on matters thus agreed on, for experience seems a sufficient test" (On The Sublime, XXXIX. 83). Reason and madness in poetry are relative to the listener. I will examine the responses of Plato, Aristotle, and Longinus to poetry and its relation to reason and the irrational. In addition, I will relate some of my own views on the topic.
Plato takes a very strong position against poetry. He deprecates the worth of poets to be taken seriously by attributing their creation of words to madness, or the irrational. As Plato states clearly in the Ion, "no man, while he retains that faculty [reason], has the oracular gift of poetry". Plato seems to imply that one is naturally in his "right mind". However, under the influence of some divine power, poets "are only the interpreters of the gods by whom they are severally possessed" (Ion, ll.519-20). Poets are human beings deficient in reason; that is why they do not deserve a place in Plato\'s Republic. According to Plato, to be inspired by and towards poetry is to be irrational, or "under the influence of Dionysus". On the other hand, reason qualifies as a lack of inspiration. The merit of reason lies on a parallel plane with other virtues such as beauty, good, and justice. Ironically, Plato is a philosopher because he is a poet. Plato speaks eloquently at times and he always finds listeners. True philosophy is poetry, virtue at its acme.
Aristotle, interested only in observation and rational analysis, contents himself by asserting that a true poet must either have a high degree of natural ability to adapt himself to other characters or else be able of entering a state of ecstatic madness. "But once the irrational has been introduced and an air of likelihood imparted to it, we must accept it in spite of the absurdity" (Poetics, XXIV. 10). By proposing that poetry is "more philosophical and a higher thing than history", Aristotle introduces the idea that poetry could potentially be more provocative for the mind than Plato had previously thought. Tragedy assumes a more authoritative position than comedy; tragedy makes sense because of its seriousness and profundity. Therefore, the "tragic plot should not be composed of irrational parts" (Poetics, XXIV. 10) and a poet may recreate the actual, but he must avoid the chaotic, the imaginary, and the impossible. Aristotle states that poetic truth passes the bounds of reason but it refrains from breaking those rules which make the real world rational.
Longinus declares that the effect of poetry can strongly excite the emotions of the listener. In the same way, he believes, the varying melodies and rhythms of poetry and oratory convey the emotions of a poet or orator