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.
Copyright protection in works created after January 1, 1978 generally lasts until 70 years after the death of the creator. Copyright in works created by businesses or before 1978 can last for 95 years from publication. After a work is no longer protected, it falls into the public domain.