observe vs perceive

observe

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

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

  • To comment on something; to make an observation. 

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

perceive

verb
  • To become aware of, through the physical senses, to see; to understand. 

  • To interpret something in a particular way 

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