leave behind vs memory-hole

leave behind

verb
  • To forget about. 

  • To pass. 

  • Used other than figuratively or idiomatically: see leave, behind. 

  • To abandon. 

  • To leave (a trace of something). 

  • To not live longer than; to be survived by. 

  • To outdo; to progress faster than (someone or something else). 

memory-hole

verb
  • To cause something or someone to be forgotten. 

How often have the words leave behind and memory-hole occurred in a corpus of books? (source: Google Ngram Viewer )