invention vs optical illusion

invention

noun
  • Something invented. 

  • The capacity to invent. 

  • The act of inventing. 

  • A small, self-contained composition, particularly those in J.S. Bach’s Two- and Three-part Inventions. 

optical illusion

noun
  • An image that is visually deceptive or misleading. 

How often have the words invention and optical illusion occurred in a corpus of books? (source: Google Ngram Viewer )