Most operas since Wagner also unfold in through-composed scenes rather than self-contained numbers and a musico-poetic synthesis of some sort is also the norm. Wagner did not (quite) invent the notion of the leitmotif, but he did develop it as a structural principle and the technique has been imitated to a greater or lesser extent by virtually all subsequent composers of opera. Those structures were themselves shaped according to tonalities and networks of ‘ leitmotifs’ – short motifs identified with specific objects (sword, spear, ring), characters, ideas or emotions. This in turn predicated a breakdown of the conventional operatic numbers – aria, duet, chorus and so on – in through-composed scenes that still retained elements of those forms but now organised in large-scale structures. Sometimes called a ‘musico-poetic synthesis’, this was a fusion of text and musical line that captured all the expressive nuances of the former in a setting that was neither recitative nor aria, but a kind of heightened arioso – somewhere between the two.

In place of the conventional melody and accompaniment that had until then characterised opera composition, he created a new way of setting the text (which he always wrote himself). Wagner’s works were revolutionary in other ways too.

Famous opera music