contemplation vs pondering

contemplation

noun
  • The act of contemplating; musing; being highly concentrated in thought 

  • The act of looking forward to a future event 

  • Holy meditation. 

  • The state of being considered or planned. 

pondering

noun
  • An act of rumination or cogitation. 

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