Beda modernus

I have already written about music that was never finished, such as the Mozart Reqiuem and (probably) Bach's Art of Fugue.  But what of music that may have been completed and was then lost, or music that was never written?  In this regard cello concertos have fared particularly badly.  The most notorious case is that of Mendelssohn who seems, from his letters, to have written a cello concerto.  However, when he sent the only copy of it to the dedicatee, it supposedly dropped off the coach and disappeared forever.  Mozart also may have written a cello concerto, the autograph of which was supposedly in the Paris Bibl. Du Conservatoire as late as 1912, dated to 1775.  However, this autograph (of K206a) has never been found, so only a 6 bar intro is now known of this work.  Haydn's most beautiful concerto, No. 1 in C major was thought to have been lost, but remarkably re-emerged in 1961 in Prague.  At least these works were all (at least partly) written.  Beethoven offered to write a concerto for the egocentric virtuoso cellist Romberg, but he refused on the grounds that he preferred to perform his own works.  It is worth noting that Romberg's 10 concertos and concertino are now of only academic interest and, to say the least,  rarely performed.   One imagines that the never-to-appear Beethoven effort would have had a more permanent place in the repertoire.
The cello is a difficult instrument to write concertos for: its normal register sits in the middle of the orchestra, which makes it difficult to make the solo part stand out: famous examples such as the Schumann one therefore tend to write for high registers.  Still, the instrument seems to have had more than the usual bad luck.
Such works have at least some hold on our imagination; but what about works that might have been written by composers who died romantically young - notably Schubert (died age 32) and Mozart (died 35)?  What operas, for example, would Mozart have written if he had lived to the same age that Monteverdi did, who produced his operatic masterpiece, the Coronation of Poppea, at the age of 75, with the Return of Ulysses the year before? 
What I want to mention is our aesthetic response to such loss.  One can indeed regret that such works never appeared; but we cannot miss them: aesthetic response is to subjective particulars, not to general ideas.  Indeed, most people will never hear a Wagner opera, and despite their reputation as pinnacles of Western music, and thus music as a whole, most people who do hear them will probably dislike them.  Furthermore, one's own taste can fluctuate through life: one can go many years without listening to a once favourite composer and then return to it again with renewed love.
One consequence of Kant's Antimony of Taste: the idea that we wish to universalise subjective aesthetic judgments, is that one cannot but feel that someone who does not appreciate, say, Parsifal, is missing something: their life would be better if they did.  Naturally enough, this notion would typically be strongly, even violently resisted by the typical Wagner-uninterested person.  It smacks of elitism, being patronising, and so on. Still, one cannot easily rid oneself of the notion, even if during a period of one's own life when such music did not interest you one did not feel necessarily impoverished. 
I want to apply this sort of thought now to religion, the aesthetics of which I must now start to turn to. 
Religion strikes me as occupying an intermediate position between science and art.  It is a delicate path to tread, and one that is constantly in threat of being collapsed into one or the other: either being seen as just bad science, or as deluding art.  Just as my tastes in particular music have waxed and waned over the years, so has my interest and participation in religion.  Yet, even one if may not miss it doing the "off" periods, religion during its "on" moments is the great experience of life that all else is interpreted in; an ecstatic reinterpretation of experience and community; an "endlessly open epiphany", as Joyce's Ulysses has been described.  Here is T. S. Eliot in Little Gidding:

"If you came this way,
Taking any route, starting from anywhere,
At any time or at any season,
It would always be the same: you would have to put off
Sense and notion. You are not here to verify,
Instruct yourself, or inform curiosity
Or carry report. You are here to kneel
Where prayer has been valid."

Religious experience, in all its humble beauty, is the great experience of life, and we should not abandon it under the pressure of those who despise it.  Such should be resisted even more than that from those who despise the high tradition of music.  Even if we know that such experience cannot be objectively demonstrated, and that those who once had it may despise it afterwards, we cannot but continue to think this, just as the case for Kantian aesthetics.  
And so we come to the great problem of our age: how do we persuade others of the value of our own religious and aesthetic experiences?  It cannot be by argument.  It cannot be by demonstration: I cannot *show* someone my experience.  
But perhaps Francis of Assisi was on the right track.  Preach the gospel at all times.  If necessary, use words.