creative work vs magnum opus

creative work

noun
  • A tangible manifestation of creative effort, such as literature, music, paintings, and software. 

magnum opus

noun
  • A great or important work of literature, music or art, a masterpiece. 

  • The best, most popular, or most renowned achievement of an author or artist, representing their major life effort. 

  • The process of working with the prima materia to create the philosopher's stone. 

How often have the words creative work and magnum opus occurred in a corpus of books? (source: Google Ngram Viewer )