Well, I've put less than 2% the thought into it than Chesterton did. As I said, his higher education was specifically art school, so I think it's much more worth considering his thoughts. Any thoughts on the few that I posted? I deliberately picked short statements that make what I hope are clear points.
The angle I think most worth considering Is the philosophical one - when subjectivism came into vogue, and nihilists were taken seriously - this is when we see the rise of movements to present everything as it is not.
When I was a Russian language student, I spent a semester in Moscow (that was the semester I got married), and our conversation instructor used the history of Russian art as a major topic and issued us all books. I fell in love with Russian art the, particularly the period of realism - from Briullov to Repin (who is simply Russia's Rembrandt imo), and though there was plenty of good stuff before that period (such as Rublev), what I saw afterward was a clear downward spiral, as Vrubel, Serebryakova (who I think particularly talented) and Shagall produced stuff that simply couldn't match up in terms of effort, beauty, clarity. Oh sure, beauty there was, still, but in comparing over time I could see a line of progression, so that by the time you hit the Soviet period it just gets downright depressing, with only a few remarkable works contrasting the general tendencies - precisely because they bucked the modern trends and "regressed" back to realism, though the talent was not as great.
The main thing is that artistic changes don't happen in a vacuum. There is a general atmosphere, a spirit of the age, which influences the art of an age, and our time is a time of unbelief, just as the Renaissance coincided with a resurgence of belief in the West. Ours is an age of pluralism, of a general abolishment of standards, and modern education has replaced classical education, and so schools can only teach "schools of thought", and do not school in the kind of discipline that produced holistic artists who were philosophical as well as artists. Rublev was great because his vision was guided by Truth. To the extent that truth is abandoned or rejected art must degrade, and the visions more and more insane, until we praise black squares and spattered colors across a canvass, and none are left to cry that the emperor has no clothes.
