Brought about by listening to Wagner's piano transcript of Beethoven's 9th (below should you have access to Spotify). I think it is sometimes easy to forget the, admitted, influence Beethoven and especially the 9th had on Wagner. All of the following is taken from Wagner's Biography "My Life" which, despite its occasional unreliability, remains some of Wagner's clearest prose work and can be read or downloaded in full and for free by clicking this link
"I now wanted to set Leubald und Adelaide (sic) to music, similar to that which Beethoven wrote to Goethe's Egmont; the various ghosts from the spirit world, who were each to display different characteristics, were to borrow their own distinctive colouring from appropriate musical accompaniment"
"On the other hand, this visit brought me a great treasure, which was responsible for leading me in a very different direction from that advised by Kuhnlein. This was the score of Beethoven's great Quartette in E flat major, which had only been fairly recently published, and of which my brother-in-law had a copy made for me. Richer in experience, and in the possession of this treasure, I returned to Leipzig to the nursery of my queer musical studies"
"As my musical instruction also did me no good, I continued in my wilful process of self-education by copying out the scores of my beloved masters, and in so doing acquired a neat handwriting, which in later years has often been admired. I believe my copies of the C minor Symphony and the Ninth Symphony by Beethoven are still preserved as souvenirs."
"Beethoven's Ninth Symphony became the mystical goal of all my strange thoughts and desires about music. I was first attracted to it by the opinion prevalent among musicians, not only in Leipzig but elsewhere, that this work had been written by Beethoven when he was already half mad. It was considered the 'non plus ultra' of all that was fantastic and incomprehensible, and this was quite enough to rouse in me a passionate desire to study this mysterious work. At the very first glance at the score, of which I obtained possession with such difficulty, I felt irresistibly attracted by the long-sustained pure fifths with which the first phrase opens: these chords, which, as I related above, had played such a supernatural part in my childish impressions of music, seemed in this case to form the spiritual keynote of my own life. This, I thought, must surely contain the secret of all secrets, and accordingly the first thing to be done was to make the score my own by a process of laborious copying. I well remember that on one occasion the sudden appearance of the dawn made such an uncanny impression on my excited nerves that I jumped into bed with a scream as though I had seen a ghost. The symphony at that time had not yet been arranged for the piano; it had found so little favour that the publisher did not feel inclined to run the risk of producing it. I set to work at it, and actually composed a complete piano solo, which I tried to play to myself. I sent my work to Schott, the publisher of the score, at Mainz. I received in reply a letter saying 'that the publishers had not yet decided to issue the Ninth Symphony for the piano, but that they would gladly keep my laborious work,' and offered me remuneration in the shape of the score of the great Missa Solemnis in D, which I accepted with great pleasure."
Below, the entire work on Spotify. It can also be heard on youtube. Much thanks to Ulysess Classical for finding this on Spotiify
"But another work of this period, an Overture in B flat major, left an indelible impression on my mind on account of an incident connected with it. This composition, in fact, was the outcome of my study of Beethoven's Ninth Symphony in about the same degree as Leubald und Adelaide (sic) was the result of my study of Shakespeare. I had made a special point of bringing out the mystic meaning in the orchestra, which I divided into three distinctly different and opposite elements. I wanted to make the characteristic nature of these elements clear to the score reader the moment he looked at it by a striking display of colour, and only the fact that I could not get any green ink made this picturesque idea impossible. I employed black ink for the brass instruments alone, the strings were to have red and the wind green ink. This extraordinary score I gave for perusal to Heinrich Dorn, who was at that time musical director of the Leipzig theatre. He was very young, and impressed me as being a very clever musician and a witty man of the world, whom the Leipzig public made much of.
"At this time I also wrote (as my third opus) an overture to Raupach's drama, Konig Enzio, in which again Beethoven's influence made itself even more strongly felt."
"As regards style and design, this work was suggested by Beethoven's Seventh and Eighth Symphonies, and, so far as I can remember, I should have had no need to be ashamed of it, had I been able to complete it, or keep the part I had actually finished. But I had already begun at this time to form the opinion that, to produce anything fresh and truly noteworthy in the realm of symphony, and according to Beethoven's methods, was an impossibility. Whereas opera, to which I felt inwardly drawn, though I had no real example I wished to copy, presented itself to my mind in varied and alluring shapes as a most fascinating form of art. Thus, amid manifold and passionate agitations, and in the few leisure hours which were left to me, I completed the greater part of my operatic poem, taking infinitely more pains, both as regards words and versification, than with the text of my earlier Feen. Moreover, I found myself possessed of incomparably greater assurance in the arrangement and partial invention of situations than when writing that earlier work."