here is a tip:I'm sure Toscanini and Dmitri Mitroupulos,both two had a kind of fotographic memory,they can see mentaly every page,every note ,and so on.From Mitroupulos i kwnew from reading,and for Toscanini,for reading too+testymony of a person who was at that time in charge of organization and rehearsals,in concerts who also knew Alfredo Casella,who also in his book "Il Pianoforte" speak about this. Regards. Gerardo Constantini.