The language of the theatre is poetic and verse, starting from the ancient Greek theatre to the 18th century. The first serious discussions about the tragedies should be written in prose language are raised in France by authors such as Trublet, Fontenelle and La Motte. But the real impact on this subject is The London Merchant, written by British playwright George Lillo in 1731. This initiative of Lillo has a mobilizing effect in Continental Europe with the efforts of Diderot and Lessing. The development of bourgeois class-consciousness underlies this intellectual and literary transformation in the art of drama. The middle-class audience finds it more realistic to see daily events and ordinary people from their own life, rather than watching superior tragic heroes in the theatre. Thus, the bourgeois class, which creates a unique form and expression style in theatre art, brings a different perception of reality to the theatre by using everyday language in playwriting. In the 19th century, the dominant language of the theatre became prose with the effect of realism and naturalism. In this article, firstly, the historical process of the transition from verse to prose was examined in the playwriting, and then the contributions of the use of everyday language in the theatre to the perception of reality were evaluated. Finally, with this change of dialogue writing, it was emphasized that the prose language gained and lost in the relationship between theatre and literature.