cloud cuckoo land vs delusion

cloud cuckoo land

delusion

noun
  • A false belief that is resistant to confrontation with actual facts. 

  • A fixed, false belief, that will not change, despite evidence to the contrary. 

  • The state of being deluded or misled, or process of deluding somebody. 

  • That which is falsely or delusively believed or propagated; false belief; error in belief. 

How often have the words cloud cuckoo land and delusion occurred in a corpus of books? (source: Google Ngram Viewer )