Thanks, CC. I suspect that Barenboim plays this piece with the pedal down all the time, but I’m not absolutely sure
… It also plays it very, very slow (6:27’)
Nice observation. But I was of course referring to LVB music that should be played with a minimum of pedal, such as the first movement of the Appassionata that I recently heard. Don't get me wrong, though, because Barenboim is quite popular. Goes to show how recognized masters can get away with things that would cause us to fail an audition.
Returning to the Moonlight, I think that dissonance plays a MAJOR role in this piece; this is all about tragic sorrow (but, as with all LVB, there is an unmistakeable hope and uplifting basis which I'll discuss briefly), and dissonance represents the pain of sorrow. So I imagine the clear harmony as love, and the dissonance as pain -- again another sharp contrast. Even with "conventional" pedaling, you can't avoid the dissonance in bar 2. Bar 2! why so early? because LVB (IMO) wanted to tell us: "dissonance is OK, we need it in this piece", and he didn't want to wait 5 bars for the background dissonance to develop naturally because the beginning is so harmonious. This bar did not have to be dissonant, so there must be a reason for its dissonance.
He then goes ahead and uses dissonance to great effect, as seen in the ninths of bars 16 and 18, where the melancholy repetition of the B is punctuated by the "painful" dissonance with the C. Since I have small hands, I play the lower note of the ninth with the LH which also provides the special control that this note demands. The almost interminable repetition of the B here is a device LVB used to great effect in many of his pieces, where the conversations with the other notes and the rhythm (cut time, like the tolling of a bell) creates music with this repetition. This answers the question, "how did he create music by just repeating a single note so many times?"
I think that LVB was particularly fond of the octave effect (eg, LH tremolo in Pathetique), and almost every melodic note of the RH is accompanied by its lower octave (as well as in the LH); therefore both notes of the octave should be clearly audible. Many recordings, especially the faster ones, emphasize the clear upper melodic lines and ignores the octave. Most audiences are quite happy with this because the mental work needed to appreciate LVB can be too much for most. Many in the audience just want their music presented simply on a silver platter, which is easier to digest. But the intent of great composers was to create infinitely deep music, which I define as wonderful music that you can listen to repeatedly without getting tired of it. The difficulty with composing those great melodies as represented by the Moonlight is that the melodies quickly become familiar and will cause boredom unless it is infinitely deep. How did he do it?
One of the (probably many) ways in which he accomplished depth is to combine so many ideas in every bar that it was impossible for the audience to pay attention to all of them at once; if a person becomes familiar with one aspect, a different one becomes noticeable the next time, so in effect there are an infinite number of permutations within a long piece if there are, say, 5 different effects in every segment.
Before counting these 5 (or more!) ideas, let me digress because there is another matter that is part and parcel of this whole presentation/composition topic. In many ways, musicians must be magicians. Both strive to control the minds of the audience. In addition, the magic works best if the audience doesn't know the trick. This is also true in music: if you can control the emotions of the audience without their knowing how you did it, it has a larger effect. Cresc. and PP, and changes in speed are obvious devices, but do not contribute substantially to depth because they are obvious. Of course, there is musical depth and structural depth; here I only discuss structural depth which seems particularly easy to spot in LVB. My point is that these structural ideas can be used by the pianist to produce music that the audience can listen to repeatedly, and wonder why it still sounds so good after so many times. It also helps you to play; in fact it would be terribly difficult to perform if the music consisted of only one familiar melodic line. This is one of the biggest advantages of the piano compared to instruments such as the violin, because the piano has this infinity of possibilities and depth that others do not (although they have their own sets of infinities to exploit).
So let's count these structural ideas in the Moonlight (most of which have been discussed). (1) dissonance vs harmony, (2) slow vs fast (3rd mvmnt) -- ie, some ideas take effect later, (3) use of repeated notes (creates tension that can be released at the end) (4) although this piece is obviously sad, it is also full of hope and strength -- how did LVB do that? I'll leave this one for you to figure out yourself, I have some of my own ideas, (5) the "insane" use of the pedal, (6) use of a major theme consisting of only one note repeated 3 times, (7) use of a constant, dissonant background in which a clear harmonic melody is superposed, (

the octave effect, (9) use of extremism (extreme slow vs fast, dissonance vs harmony, pedal vs no pedal, sad vs hope), etc., combined with doubtlessly many musical ideas. Magic!