I have enjoyed most particularly reading the correspondence between Gustav Mahler and Richard Strauss. The genuine friendship, competitiveness and support that thread through their communications are life lessons for us all.

This quote is talking about the enjoyment of reading the letters between Gustav Mahler and Richard Strauss. The quote is saying that the correspondence between them showed genuine friendship, competition, and support that can be learned from by everyone. It is suggesting that their interactions with each other had positive qualities that could be beneficial for everyone to learn and consider.