whether to move or not, its tottering neighbour comes to a quicker decision, and the work of destruction, gathering momentum as it goes on, rushes headlong to the final collapse. These instances are all different, but they suggest the same abstract vision, that of an effect which grows by arithmetical progression, so that the cause, insignificant at the outset, culminates by a necessary evolution in a result as important as it is unexpected. Now let us open a children's picture-book; we shall find this arrangement already on the high road to becoming comic. Here, for instance—in one of the comic chapbooks picked up by chance—we have a caller rushing violently into a drawing-room; he knocks against a lady; who upsets her cup of tea over an old gentleman, who slips against a glass window which falls in the street on to the head of a constable, who sets the whole police force agog, etc. The same arrangement reappears in many a picture intended for grownup persons. In the "stories without words" sketched by humorous artists we are often shown an object which moves from place to place, and persons who are closely connected with it, so that through a series of scenes a
