explain vs set forth

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. 

set forth

verb
  • To state; describe; give an account of. 

  • To present for consideration; to propose. 

  • To begin a journey or expedition. 

  • To start. 

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