observe vs perform

observe

verb
  • To follow or obey the custom, practice, or rules (especially of a religion). 

  • To take note of and celebrate (a holiday or similar occurrence); to follow (a type of time or calendar reckoning). 

  • To notice or view, especially carefully or with attention to detail. 

  • To comment on something; to make an observation. 

perform

verb
  • To behave in accordance with, and thereby in turn shape, (a social notion or role). 

  • To fulfill contractually agreed-to terms. 

  • To exhibit an expected pattern of behavior; to function; to work. 

  • To act in accordance with (a contract); to fulfill one’s terms of (a contract). 

  • To do (something); to execute. 

  • To do (something) in front of an audience, such as acting or music, often in order to entertain. 

  • To behave theatrically so as to give the impression of (a quality, character trait, etc.); to feign. 

  • To behave in ways that carry meaning in social contexts. 

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