equilibrium vs serenity

equilibrium

noun
  • The state of a body at rest or in uniform motion in which the resultant of all forces on it is zero. 

  • Mental balance. 

  • The condition of a system in which competing influences are balanced, resulting in no net change. 

  • The state of a reaction in which the rates of the forward and reverse reactions are the same. 

serenity

noun
  • A lack of agitation or disturbance. 

  • The state of being serene; calmness; peacefulness. 

  • A title given to a reigning prince or similar dignitary. 

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