There seem to be two main moral lessons that we can draw from this excellent and surprising tale. The first lies in the way in which Mrs. Slade completely underestimates her friend, Mrs. Ansley, and believes that she is better than her because of the way in which Mrs. Slade is aware of Mrs. Ansley's involvement with her husband and how she manipulated Mrs. Ansley to go to the Colosseum at night in the attempt of killing her off. Mrs. Slade presents herself as a woman who likes to feel in control, and she tells her friend all of this with a grim satisfaction of somebody who knows more than Mrs. Ansley does. However, she is made to realise at the end that the reverse is true, and although she likes to be in control of the facts, Mrs. Ansley reveals the true father of her daughter in a way that completely shocks Mrs. Slade and shows how she underestimates her old friend.
The second lesson I think we cna draw from this story concerns the way in which these two old friends have remained friends in spite of all the barriers between them. It shows how the demands of society often force us to do things and to maintain relationships that we actually would rather ignore and drop. This story suggests that we are not free to live our own lives, and that society actually presents demands on us that must be met.