Mrs. Gradgrind is passive, sickly, dim-witted, and not very present in the novel or in her children's lives. Gradgrind basically says that he married her because she had no personality whatsoever and thus would not get in the way of his education plans for his kids. He's right. Mrs. Gradgrind has one bright moment just before she dies. She suddenly realizes that Louisa and Tom are missing a key ingredient in becoming normal human beings. Even then, however, she can't actually say what that might be, and in any case it's already too late.