impose vs observe

impose

verb
  • to enforce: compel to behave in a certain way 

  • To practice a trick or deception (on or upon). 

  • To arrange in proper order on a table of stone or metal and lock up in a chase for printing; said of columns or pages of type, forms, etc. 

  • To establish or apply by authority. 

  • To lay on, as the hands, in the religious rites of confirmation and ordination. 

  • to be an inconvenience (on or upon) 

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. 

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