According to the following:
- At this point it is worth recalling a recent interview with Daniel Barenboim who, in comparing these two rostrum giants, made the interesting point that while in youth the privileged Furtwängler was able to work with good orchestras, the under-privileged Toscanini had the unenviable task of drilling under-par provincial players. So while precision and tight ensemble became life-long preoccupations with Toscanini, Furtwängler had the luxury of setting his sights elsewhere. Furtwängler’s Notebooks (Quartet Books: 1989) include an extraordinary entry on ‘Toscanini in Germany’ where, in the context of reporting on Toscanini’s Beethoven, he cites a passage where ‘the functional meaning of the modulations in the long term, which in absolute music such as Beethoven’s play such a different role, seem to be completely unknown to Toscanini’s naïve feeling for opera music’. This candid confession seems to me to encapsulate a crucial difference between the two conductors — later terms in the same entry include ‘Beethovenian attitude’ and ‘tensed stillness’ — where Furtwängler’s intuition is aligned with authentic expression and Toscanini’s manner more with immaculate execution and technique. And yet while Toscanini was widely lionised as a unique phenomenon, a sort of musical cleansing agent if you will, Furtwängler’s more individualistic approach attracted equal levels of adoration.
https://www.gramophone.co.uk/feature/wilhelm-furtwangler-the-man-and-myth