Hari Seldon was a great mathematician. He studied math that dealt with human civilizations and was called psychohistory. He very correctly predicted in the period of three hundred years the fall of the Galactic Empire in which lived a quadrillion of people. He also prophesized that after the decline there will ensue thirty thousand years of complete barbarism.
In order to shorten that period to a single millennium he gathered many people around himself with the task of founding an Encyclopedia where it could incorporate and accumulate all the human knowledge known hitherto. The purpose of Encyclopedia is to gain knowledge from, for barbarians. It will cut their time of misery because they wouldn’t have to learn any science anew.
But the Emperor of Trantor, the head planet of the Galactic Empire, is politician. He’d not allow any disturbing elements like Hari Seldons saying here and there to the people that the Empire has 3 centuries left to live. So he sent Hari Seldon and his followers to a planet Terminus in exile. In Terminus they settled a scientific community with the only one purpose, to continue working on Encyclopedia.
After fifty years the encyclopedists encountered face to face with a serious crisis. A mayor of Terminus, Salvor Hardin handled the problem very cautiously. He used religion as his weapon against Anacreonian menace. He said to the ruler of Anacreon that if you attack on Terminus, millions of priests will consider the act sacrilegious and come to overthrow your Kingdom form throne and pull you apart as warm bread. That saved a day and made Hardin famous in Terminus. There are also other such-like crises in the book.I first had read this book at school in Turkish. Since then I’d quite forgotten the plot line and I decided to read it again in English. If you paid attention there’s no mention of thermonuclear power in the book but only of the nuclear one. It’s because at the time of writing this book the world hadn’t known yet about the fusion of light Hydrogen atoms into Helium which happens in the Sun.