Not so long ago I read a note by a European string player who was a young student in the 1890s. He observed that gut strings were universal before the First World War. When they began to appear in the first decade of the twentieth century, they were considered functional but inferior, and mainly used by students. Wartime shortages then made them a regrettable necessity for working professionals and orchestras. I haven't had a chance to investigate this properly, but the source is unquestionable. Wind instruments constantly evolved and were "improved" over the course of the nineteenth century, with its genius for mechanical inventions. This gives us an idea of when and how this crucial divide separated modern musicians and audiences from the techniques and sounds of earlier composers—meaning Mahler, not Mozart. There is still some general idea in the mind of the public that historical instruments and performance practices concern primarily music of the Baroque and Classical periods, but musicians have been applying the fruits of performance history to Romantic music for over twenty years—with gratifying results.