And again Neal Cloud and Babe, the big blue ox, hit the road. And as he rolled the physicist mulled over in his mind the assignment to which he had set himself. Like fire, only worse, intra-atomic energy was a good servant, but a terrible master. Man had liberated it before he could really control it. In fact, control was not yet, and perhaps never would be, perfect. Up to a certain size and activity, yes. They, the millions upon millions of self-limiting ones, were the servants. They could be handled, fenced in, controlled; indeed, if they were not kept under an exciting bombardment and very carefully fed, they would go out. But at long intervals, for some one of a dozen reasons--science knew _so_ little, fundamentally, of the true inwardness of the intra-atomic reactions--one of these small, tame, self-limiting vortices flared, nova-like, into a large, wild, self-sustaining one. It ceased being a servant then, and became a master. Such flare-ups occurred, perhaps, only once or twice in a century on Earth; the trouble was that they were so utterly, damnably _permanent_. They never went out. And no data were ever secured: for every living thing in the vicinity of a flare-up died; every instrument and every other solid thing within a radius of a hundred feet melted down into the reeking, boiling slag of its crater. Fortunately, the rate of growth was slow--as slow, almost, as it was persistent--otherwise Civilization would scarcely have had a planet left. And unless something could be done about loose vortices before too many years, the consequences would be really serious. That was why his laboratory had been established in the first place. Nothing much had been accomplished so far. The tractor beam that would take hold of them had never been designed. Nothing material was of any use; it melted. Pressors worked, after a fashion: it was by the use of these beams that they shoved the vortices around, off into the waste places--unless it proved cheaper to allow the places where they had come into being to remain waste places. A few, through sheer luck, had been blown into self-limiting bits by duodec. Duodecaplylatomate, the most powerful, the most frightfully detonant explosive ever invented upon all the known planets of the First Galaxy. But duodec had taken an awful toll of life. Also, since it usually scattered a vortex instead of extinguishing it, duodec had actually caused far more damage than it had cured.