The fleet which had been preparing to follow the leading fort was suddenly stopped; it halted indecisively. Then the _Thought_ became visible as its great golden letters showed suddenly, streaking up from distant space. Every ship turned cosmic and moleculars on it. The cosmic rebounded from the cosmium walls, and from the artificial matter that protected the eyes. The moleculars did not affect either, but the invisible protective sheet that the _Thought_ was maintaining in the Ortolian atmosphere became misty as it fought the slight molecular rebounds. The _Thought_ went into action. The fort which remained was the point of attack. The fort had turned its destructive ray on the cosmium ship with the result that, as before, the cosmium slowly disintegrated into puffs of cosmic rays. The vapor seemed to boil out, puff suddenly, then was gone. Arcot put up a wall of artificial matter to test the effect. The ray went right through the matter, without so much as affecting it. He tried a sheet of pure energy, an electro-magnetic energy stream of tremendous power. The ray bent sharply to one side. But in a moment the Thessians had realigned it. "It's a photonic stream, but of some type that doesn't affect ordinary matter, but only artificial matter such as lux, relux, or cosmium. If the artificial matter would only fight it, I'd be all right." The thought running through Arcot's mind reached the others. A tremendous burst of light energy to the rear announced the fact that a Thessian had crashed against the artificial matter wall that surrounded the ship. Arcot was throwing the Thessian destructive beam from side to side now, and twice succeeded in misdirecting it so that it hit the enemy machines. The _Thought_ sent out its terrific beam of magnetic energy. The ray was suddenly killed, and the fort cruised helplessly on. Its driving apparatus was dead. The diffused cosmic reached out, and as the magnetic field, the relux and the cosmics interacted, the great fort was suddenly blue-white--then instantly a dust that scattered before an enormous blast of air. From the _Thought_ a great shell of artificial matter went, a visible, misty wall, that curled forward, and wrapped itself around the Thessian ships with a motion of tremendous speed, yet deceptive, for it seemed to billow and flow. A Thessian warship decided to brush it away--and plowed into inconceivable strength. The ship crumpled to a mass of broken relux. The greater part of the Thessian fleet had already fled, but there remained half a hundred great battleships. And now, within half a million miles of the planet, there began a battle so weird that astronomers who watched could not believe it. From behind the _Thought_, where it hung motionless beyond the misty wall, a Thing came. The Thessian ships had realized now that the misty sphere that walled them in was impenetrable, and their rays were off, for none they now had would penetrate it. The forts were gone.