I have mislaid my copy of this fabulous book and am really glad to see that it is possible to obtain used copies through Amazon.
Lotte Lehmann was a very famous soprano in Europe between the Wars and was particularly associated with Richard Strauss. I bought a copy of this book in the 1980s when I was studying singing and found it a brilliant way of learning how to prepare a vocal performance. The approach that Lehmann has is to create an entire internal narrative around the song to make the singer appear to be an actor within a scene [to my mind anyway]. You may not agree with the narratives that Lehmann writes about and there is no reason why singers can't create their own. If a singer has enough of this mental narrative in his [sorry about the masculine] head, he is more likely to give a performance of real character and the song is less likely to be just bland and pretty.
I would recommend this book to anyone to anybody who aspires to sing and also to anyone who enjoys listening to good singing.