placid vs soothing

placid

adj
  • calm and quiet; peaceful; tranquil 

soothing

adj
  • Tending to soothe. 

  • Giving relief. 

  • Freeing from fear or anxiety. 

noun
  • The act by which somebody is soothed. 

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