text: The Accademia 's uncontested star , the great David ( which once stood in the Piazza della Signoria , now substituted by a life-size copy ) , provides the perfect object lesson of the finished product , a hero infused with all the contained energy needed to hurl that stone at Goliath .
  
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  In the Piazza della Signoria , the original statue of David still stands where it was first erected .