text: Holiness has been long ago defined.
  
  In fact, the pagan Aristotle got quite close to it with his definition of happiness, which is totally unknown to today's crowd, including sadly most Catholics. 
  
  A "whole life well lived" (virtuous, moral) was Aristotle's definition of happiness. 
  
  Aquinas took that long view - a life long view of never quite getting there until death - and elevated it.
  
  Holiness is living in unity with God's will, totally corresponding to His will for the sake of His glory (not for our sake).  Holiness has the Other, Himself, built into it, unlike Aristotle.    
  
  Aquinas showed that all human virtues (the matter of the Greeks) at their vanishing point..or their point of perfection touch on the good of God. 
  
  And so happiness (properly understood in terms of this deeper Greek meaning) and Holiness are highly related. 
  
  Holiness is partaking in the divine life of the Trinity, our thoughts and desires become what He planned for us.
  
  Inclined plane, a lifetime's work.