Once again, the book is split up into pieces. Probably published serially?? The first piece is pretty brief and forgettable. An ambitious general from the remnants of the decaying Empire begins a campaign against the Foundation. The Foundation is losing badly but at the last minute the Emperor recalls the general and ends hostilities. It turns out they were saved by psychohistory…the latest in a series of weak Emperors would naturally feel threatened by a successful general and would work to keep him in line. General’s with the ability to do so would focus their efforts on gaining and maintaining the imperial throne. Therefore the Foundation is safe from outside intervention. *Yawn!*
The second vignette about the Mule is the most memorable bit of the Foundation trilogy for me. It’s kind a counterpoint to the first vignette – an outside force once again threatens and actually conquers the Foundation. But how is this possible, since we’ve just been told how conquest by an outside force is impossible by the prevalent psychohistorical conditions? The answer is that the Mule is a mutant, which breaks an assumption of good old Hari Seldon that human nature would remain constant. The Mule has the ability to manipulate the emotions of others – he can make loyal followers in an instant as well as breaking down the fighting spirit of his enemies. Luckily, the heros of the story prevent him from finding out the location of the Second Foundation. And he’s infertile (like a mule; get it?) so once he passes, everything pretty much goes back to normal.
See my thoughts on the final book in the Foundation series, Second Foundation.