There is another quality in which Charles Dickens is supreme--in purity. Here is a writer who is realistic, if ever any writer was, in the sense of having closely observed the lowest strata of city life, who has drawn the most miserable outcasts, the most abandoned men and women in the dregs of society, who has invented many dreadful scenes of passion, lust, seduction, and debauchery; and yet in forty works and more you will not find a page which a mother need withhold from her grown daughter. As Thackeray wrote of his friend:--"I am grateful for the innocent laughter and the sweet and unsullied page which the author of _David Copperfield_ gives to my children." We need not formulate any dogma or rule on such a topic, nor is it essential that all books should be written _virginibus puerisque_; but it is certain that every word of Charles Dickens was so written, even when he set himself (as he sometimes did) to describe animal natures and the vilest of their sex. Dickens is a realist in that he probes the gloomiest recesses and faces the most disheartening problems of life: he is an idealist in that he never presents us the common or the vile with mere commonplace or repulsiveness, and without some ray of humane and genial charm to which ordinary eyes are blind. Dickens, then, was above all things a humourist, an inexhaustible humourist, to whom the humblest forms of daily life wore a certain sunny air of genial mirth; but the question remains if he was a humourist of the highest order: was he a poet, a creator of abiding imaginative types? Old Johnson's definition of humour as "grotesque imagery," and "grotesque" as meaning some distortion in figure, may not be adequate as a description of humour, but it well describes the essential feature of Charles Dickens. His infallible instrument is caricature--which strictly means an "overload," as Johnson says, "an exaggerated resemblance." Caricature is a likeness having some comical exaggeration or distortion. Now, caricature is a legitimate and potent instrument of humour, which great masters have used with consummate effect. Leonardo da Vinci, Michael Angelo, Rembrandt, Hogarth, use it; but only at times, and in a subsidiary way. Rabelais, Swift, Fielding, use this weapon not unfrequently; Shakespeare very sparingly; Goldsmith and Scott, I think, almost never. Caricature, the essence of which is exaggeration of some selected feature, distortion of figure, disproportion of some part, is a potent resource, but one to which the greater masters resort rarely and with much moderation.