"Now, of course, our Council of Scientists has been working on the problem of a defense against the Ray. But the only thing they've come up with is a vague idea. They believe that there is a substance which they call 'tridium,' which would absorb or neutralize the Photo-Atomic Ray. They don't know what tridium looks like, but by spectro-analysis they know that it exists on the planet Saturn. So I am sending you with an expedition to Saturn to find, if you can, the substance known as 'tridium,' and bring some of it back if possible." "Saturn!" gasped the decurion. "I said it would be dangerous," Argallum said, bleakly. "No human being has ever set foot on the planet, and very little is known about it. But that's where you'll find tridium, if we're to believe Saturn's spectrum. You will have the latest, fastest Cosmos Carrier. You will have a completely equipped expedition. You will have for assistants the best young men we can find. As head of the expedition, you will be promoted to the rank of centurion. Do you accept the assignment?" "Yes, sir," said Dynamon, unhesitatingly, "I accept the assignment." * * * * * Dynamon walked thoughtfully out of Government city by the North Gate. The sentry noticed that his helmet was now adorned with the badge of centurion, and came to a smart salute. Dynamon went past him without seeing him, and the sentry glared after the new centurion disapprovingly. Lost in thought, Dynamon kept on walking until he came to with a start, and found himself in the middle of the shopping district. The sun was getting uncomfortably warm and Dynamon switched off the electric current that heated his long cloak and looked around him. A sign in a shop window said, "Only fourteen more shopping days before the Twenty-fifth of December." Dynamon sighed. He wouldn't be around on this Twenty-fifth and it was going to be a very gay one. It was to be the nine hundredth anniversary of the Great Armistice--from which had come the unification of all the peoples of the Earth. Dynamon sighed again. The long peace was threatened. The Earth, in this year of grace 3057, was a wonderful place to live in, and Copia was the political and cultural center of the Earth. For nine hundred years now, the peoples of the Earth had lived at peace with one another as members of a single integrated community. The World-State had grown into something which that war-torn handful of people back in 1957 could scarcely have imagined. No longer did region war against region, or group against group, or class against class. Humanity had finally united to fight the common enemies--death, disease, old age, starvation.