Later in the novel Mary will try to give the peasants all the grain in the stores but they refuse it, are in fact nearly hostile to her. And so even she who knows the serfs, knows what they endure has a hard time doing good. Pierre, then, is totally out of his element and is useless. This is Tolstoy’s condemnation of the rich class who think giving money is the same as doing good. They do more harm actually.