“But the last event is practically an _effect_ of the first, isn’t it? And yet you call it a _cause_ of it!” Arthur pondered a moment. “The words are rather confusing, I grant you,” he said. “Will this do? The last event is an effect of the first: but the _necessity_ for that event is a cause of the _necessity_ for the first.” “That seems clear enough,” said Lady Muriel. “Now let us have the problem.” “It’s merely this. What object can we imagine in the arrangement by which each different size (roughly speaking) of living creatures has its special shape? For instance, the human race has one kind of shape—bipeds. Another set, ranging from the lion to the mouse, are quadrupeds. Go down a step or two further, and you come to insects with six legs—hexapods—a beautiful name, is it not? But beauty, in our sense of the word, seems to diminish as we go down: the creature becomes more—I won’t say ‘ugly’ of any of God’s creatures—more uncouth. And, when we take the microscope, and go a few steps lower still, we come upon animalculæ, terribly uncouth, and with a terrible number of legs!” “The other alternative,” said the Earl, “would be a _diminuendo_ series of repetitions of the same type. Never mind the monotony of it: let’s see how it would work in other ways. Begin with the race of men, and the creatures they require: let us say horses, cattle, sheep, and dogs—we don’t exactly require frogs and spiders, do we, Muriel?” Lady Muriel shuddered perceptibly: it was evidently a painful subject. “We can dispense with _them_,” she said gravely. “Well, then we’ll have a second race of men, half-a-yard high——” “—who would have _one_ source of exquisite enjoyment, not possessed by ordinary men!” Arthur interrupted. “_What_ source?” said the Earl. “Why, the grandeur of scenery! Surely the grandeur of a mountain, to _me_, depends on its _size_, relative to me? Double the height of the mountain, and of course it’s twice as grand. Halve _my_ height, and you produce the same effect.” “Happy, happy, happy Small!” Lady Muriel murmured rapturously. “None but the Short, none but the Short, none but the Short enjoy the Tall!” “But let me go on,” said the Earl. “We’ll have a third race of men, five inches high; a fourth race, an inch high——” “They couldn’t eat common beef and mutton, I’m sure!” Lady Muriel interrupted. “True, my child, I was forgetting. Each set must have its own cattle and sheep.” “And its own vegetation,” I added. “What could a cow, an inch high, do with grass that waved far above its head?”