La Mara assumed first that Therese Brunsvik was (secretly) Beethoven's "Immortal Beloved," based mainly on second-guessing by some of the later descendants of the Brunsvik family whom she had interviewed. The major value of La Mara's first book is in publishing of Therese's Memoirs - a very lively and readable account, not only of her own (long and reasonably happy) life, but also of her sister Josephine's (short and unhappy) life. And, of course, her never-ending adoration of Beethoven. In 1920, after discovering various letters and many other documents (at least what was accessible in the aftermath of the First World War), she corrected her previous view and was now convinced that Josephine was the One. La Mara was the first to get it right.