Complex sentence: An important source for earlier conceptions concerning Mozart's method of composition was the work of the early 19th century publisher Friedrich Rochlitz, who propagated a number of anecdotes about Mozart that were long assumed authentic, but with more recent research are now widely doubted.
Split into simpler sentences: An important source for earlier conceptions concerning Mozart's composition method was the work of the early 19th century publisher Friedrich Rochlitz. He propagated anecdotes about Mozart that were long assumed authentic, but with more recent research are now widely doubted.