Flat characters were called "humours" in the seventeenth century, and are sometimes called types, and sometimes caricatures. In their purest form, they are constructed round a single idea or quality: when there is more than one factor in them, we get the beginning of the curve towards the round. The really flat character can be expressed in one sentence such as "I never will desert Mr. Micawber." There is Mrs. Micawber--she says she won't desert Mr. Micawber, she doesn't, and there she is. Or: "I must conceal, even by subterfuges, the poverty of my master's house." There is Caleb Balderstone in _The Bride of Lammermoor_. He does not use the actual phrase, but it completely describes him; he has no existence outside it, no pleasures, none of the private lusts and aches that must complicate the most consistent of servitors. Whatever he does, wherever he goes, whatever lies he tells or plates he breaks, it is to conceal the poverty of his master's house. It is not his idée fixe, because there is nothing in him into which the idea can be fixed. He is the idea, and such life as he possesses radiates from its edges and from the scintillations it strikes when other elements in the novel impinge. Or take Proust. There are numerous flat characters in Proust, such as the Princess of Parma, or Legrandin. Each can be expressed in a single sentence, the Princess's sentence being, "I must be particularly careful to be kind." She does nothing except to be particularly careful, and those of the other characters who are more complex than herself easily see through the kindness, since it is only a by-product of the carefulness. One great advantage of flat characters is that they are easily recognized whenever they come in--recognized by the reader's emotional eye, not by the visual eye, which merely notes the recurrence of a proper name. In Russian novels, where they so seldom occur, they would be a decided help. It is a convenience for an author when he can strike with his full force at once, and flat characters are very useful to him, since they never need reintroducing, never run away, have not to be watched for development, and provide their own atmosphere--little luminous disks of a pre-arranged size, pushed hither and thither like counters across the void or between the stars; most satisfactory.