Why imperfect operas like Don Carlo are more interesting than perfect ones

In the 62 years since I first heard and saw Don Carlo, in the famous and long-lasting production by Visconti at the Royal Opera, my feelings about it have grown ever stronger, both in passionate attachment and in critique. Imperfect operas, like other imperfect phenomena, can be more interesting than perfect ones, because they’re more thought-provoking, more enticing.