The idea of the Foundation is a really basic one. Asimov postulates, what if sociology and psychology were real sciences? Thus, these two fields would have all the predictive power that real sciences possess. The catch is that the theories could only predict masses of people, not individuals. A far comparison is made with the Ideal Gas Law. For dealing with masses of gasses (that rhyme makes me smile) the Ideal Gas Law predicts with a very high level of certainty. But, try and use it to analyze one atom/molecule of a certain gas and the Law falls apart.
From that wellspring comes the story of a Galactic Empire in decay. When the Empire finally falls it will be the dawn of an age of barbarism that will last for 10,000 years. To combat this fate, the greatest pshychohistorian of the time, Hari Seldon, creates two Foundations. The Foundations are to act as bastions of knowledge. The Foundations should be able to reduce the age of barbarism down to 1,000 years and set up the Second Galactic Empire. The story mostly follows the First Foundation and Seldon’s plan. Seldon appears to guild his Foundation from time to time in the form of pre-recorded messages automatically triggered when his calculations suggest a crisis will emerge.
Asimov is masterful at jumping through time. The first three novels cover around 300-400 years of history. There are, obviously, a lot of characters but each is fresh and unique. The First Foundation slowly becomes more and more prominent as galactic force, but often uses non-violence to solve its problems. The Second Foundation remains a mysterious force until the end of the second book. The second book also marks a shocking turn of events that really set the hook deep. I couldn’t stop reading when the character of The Mule was introduced.
I am afraid to write more because I am afraid I will let some of it slip. I made the mistake of reading about the series prior to reading it, so some aspects of the series was not as surprising as it should have been. I will not make the same mistake when talking about this awesome series.
I strongly recommend The Foundation Trilogy, it was very imaginative, cleverly written, very solid in terms of plot and story, and above all fun.