At the beginning of this article the author draws attention to the fact that during recent years a sizeable body of so far totally unknown source material concerning Busoni has come to light, which makes it possible to carry out a much fuller reconstruction of his views on opera theatre than was possible only a few years earlier. Busoni was constructing his poetics of opera theatre above all in opposition to veristic aesthetics and to the musical drama of Wagner. His hostility towards verism was closely linked to his enthusiasm for the work of German Romantic ironists, in particular E.T.A. Hoffman. Although Busoni never made it clear directly, he adopted from the latter the seraphionic principle, which consisted in intertwining closely the fairy-tale element with the 'real' life of the characters in operatic librettos. As an opponent of verism, Busoni rejected the inclusion in librettos plots with erotic themes (he was of the opinion that eroticism belongs to life, and not art), and as a consequence of this view he rejected the convention of the love duet. Referring to Busoni's division of opera into the 'magic mirror' and the 'mirror of laughter', the author shows that in case of the latter type, the inspiration for it was probably provided by the well known essay by Ch. Baudelaire 'De l'essence du rire', which sketches out the idea of comique absolu. The main aspects of Busoni's views on the construction of opera librettos were the significance attached to the problem of manipulating keywords (Schlagwort), and the postulate of giving the dramatic action a fragmentary character. Chronological gaps caused by adopting this principle should be filled in by the music which, according to Busoni, should also carry other important dramatic functions. The most important of these were to concentrate the composer's efforts on revealing the inner psychological landscape of the particular dramatis personae, and to renounce trying to illustrate the events visible on the stage. The second of these postulates was closely linked to the suggestion that music, as far as possible, should include in its influence also events taking place beyond the stage area (in such a case its function might be described as analogous to teichoscopy). Busoni was a declared opponent of the concept of 'leitmotif' and 'unendliche Melodie', put forward by Wagner. In place of the rejected leitmotif, which ensured dramatic-musical unity in the operas of Wagner and his imitators, Busoni recommended the introduction of forms typical for absolute music (e.g. a cycle of variations or a dance suite), which should guarantee dramatic-musical cohesion of particular scenes and even acts (if one admits this postulate to be one of the most momentous ones, one could attach the label of 'absolute opera' to the concept of opera created by Busoni). In his writings Busoni also devoted some attention to the theatrical aspects of opera performance. One of the most important statements in this area is the claim that the singer should perform his part in such a manner as to continuously remind the audience of the artificial character of the actions undertaken and in this way to keep destroying the stage illusion. Levelling out of the effect of the so-called fourth wall was intended to stimulate the audience towards independent thinking and, as a result, towards creating their own interpretations of the work. Busoni also thought that one way of saving the opera, which in his view was an ossified genre, was to re-theatricalise it. This could be done by linking it to, among others, the traditions of commedia dell'arte and dolls' theatre. In the case of the latter, Busoni was clearly influenced by the aesthetics of H. Kleist, but he enriched those ideas by some references to the concept of the doll put forward by R.M. Rilke and Vittorio Podrecca, the director of Teatro dei Piccoli, famous in the second decade of the twentieth century. At the end of the article the author indicates the works and the artists who were influenced by the theory proposed by Busoni. One of the most important pieces of evidence for its influence is the concept of the so-called Musikoper, i.e. an opera constructed using means typical for absolute music (The best known examples of such work are A. Berg's ' Wozzeck' and P. Hindemith's 'Cardillac', written at the same time as Busoni's unfinished 'Doktor Faust' (1918--1924), but the influence of similar thinking can also be discerned in the later 'Il Prigioniero' by Dallapiccola). The clearest imprint of Busoni's ideas on opera theatre is to be found both in the work and in the aesthetic formulated by K. Weill (a devoted pupil of Busoni), and in Brecht's concept of epic theatre, created as a result of adopting the views of the Italian thinker and composer. Traces of theatrical aspects of Busoni's ideas can also be seen in the one-act piece 'Der Mond' by C. Orff, a composer who during the 1940s used to appeal directly to the theories of the creator of Doktor Faust. One of the final manifestations of the fascination by Busoni's thought (but also his works for the stage) remains so far the chamber opera 'Faust und Yorick' (1976) by W. Rihm.