Why is ‘Murder in the Cathedral’-- by T.S. Eliot called a poetic play?

A close reading of Eliot’s treatise on drama and poetry from ‘The Music of Poetry’ (1942), Poetry and Drama ((1951) and the Need for Poetic Drama (Listeners 16-411, Nov1936) will surely underline his aim as a dramatist.
Commending Shakespeare’s use of blank verse to accommodate colloquial speech of the age, he pointed out how reality was not compromised but enriched with verse rhythms.
To Eliot only poetic drama has the ability to lay forth the dramatic action of the world expressed in music, because it is music that connects the ultimate reaches of our feelings and with the reality of the mundane world and its chaos.
Eliot being a writer of ‘Classical’ disposition couldn’t concede anything that was superfluous or irrelevant. So tracing the roots of ‘Murder in the Cathedral’ one may go as back as to Classical Greek drama influenced by Aeschylus incorporating the very element of dramatic imagination—religion, ritual, purgation and renewal—though it is also a Christian Play.
It is seemingly tough to achieve a complete segregation of one aspect from another as the versification and the style are as inextricably linked with the theme as with the force of a particular situation within the play, quite significantly with the technique of alteration similar to that of ‘Stichomythia’ in Greek tragedy, evident in the speech alternately spoken by the chorus, Priests and the tempters, which resembles the Liturgy during a Christian mass.
Undeniably the plot, theme, characters and verse are but indispensable parts of one integrated whole. The dexterous use of ritualised form, the verbal imagery, the varying flow of metrical rhythm provides the play with its very spirit essentially poetic that concentrates upon theme seen in singleness.