enchain vs explain

enchain

verb
  • To restrain with, or as if with, chains. 

  • To link together. 

explain

verb
  • To make plain, manifest, or intelligible; to clear of obscurity; to illustrate the meaning of. 

  • To give a valid excuse for past behavior. 

  • To make something plain or intelligible. 

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