cocoon vs insulate

cocoon

verb
  • To withdraw into such a case. 

  • To envelop in a protective case. 

noun
  • The silky protective case spun by the larvae of some insects in which they metamorphose, the pupa. 

  • Any similar protective case, whether real or metaphorical. 

insulate

verb
  • To separate, detach, or isolate. 

  • To separate a body or material from others, e.g. by non-conductors to prevent the transfer of electricity, heat, etc. 

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