Nicole Kidman played the part of an idiot. Any idiot can get mad and be in denial for days on end. Any idiot can get tangled up in a contest of wills in trying to punish a youngster.
The acting that more intrigues me, I think, is that of Bertha Mills and Mr. Tuttle and Lydia. Bertha Mills is a kindly person, who is trying to guide Grace to discover Grace's denial of being dead. Mr. Tuttle tries to do his part in an awkward way. I certainly can identify with being awkward and making people angry, who really don't know.
Knowing that everyone is dead in the movie, except for a short scene with a few living persons, called Intruders, takes the mellow dramma out of it, yet the actors and children are screaming and yelling excitedly, but really about nothing. The actual violence took place before the start fo the movie, and we never see the act of a violent double murder and suicide.
The movie is really an illustration of the factors that led Grace to treat her servants in a manner that they felt justified in leaving without notice, and the righteous frustration of Grace. leading to her "Madness" which resulted in her smothering her children with pillows. Killing her children seemed also out of frustration with their father, her husband, having voluntarily gone off to war.
Set against the background of reading passages from the Bible. I find a certain instruction in parenting skills from the gentle comments of Mrs. Mills. As a parent, it is easy for me to fly off the handle, more than occasionally. I find the patience displayed by the servants to be instructive, and inspiring.
I personally could use more calming approaches when facing uptight people in tense situations.