Debussy wanted to distance himself from what he considered the emotional excess of the Romantics and instead wanted to write music that, through sound, created an ambience similar to that of the Impressionist painters and Symbolist poets of his day.
All books initially copyrighted in the US from 1964 through 1977 have had their copyrights automatically renewed (by law) and the copyrights are still in force. The initial copyright term was 28 years; the renewal was for 67 more years.
Book authors may sell their copyright to the publisher. Alternatively, they might receive as a royalty a certain amount per book sold. It is common in the UK for example, for authors to receive a 10% royalty on book sales.