Foundation and Earth did not satisfy avid readers of Asimov (and fans of the Foundation series). After all, it was still only covering a period midway during the 1000 year period that was required to establish the second Galactic Empire, and neither covered the period after that, nor did it cover the period required for the establishment of Galaxia. Asimov’s widow Janet revealed after his death that Asimov was unexpectedly somewhat of a loss after Foundation and Earth to write about what happened post that period. He ran out of ideas, and hence went back to detail the Foundation periods in more detail, with Prelude to Foundation, and Forward the Foundation. Further, Foundation and Earth did not have a very gripping continuous story line, almost with individual stories tending to a final end (that was supposed to establish the robotic theme that combined the Robot Series, the Foundation Series, and the Empire Series).

Foundation and Earth covers the time period immediately after the decision by Trevize in Foundation’s Edge to use the basis of Gaia for building up a true Galaxia. However, he continues to have doubts, and is not sure whether he has made the right decision. He decides to continue searching for Earth, sure that the fact that Earth has tried to remove all traces of itself means that once he found Earth, there must be something there that would help him confirm his decision. So he sets out on an expedition along with Golan Trevize and and Bliss (a representative of Gaia) and travel to a number of planets, trying to get traces of the location of Earth.
They reach Comporellon, where they are imprisoned since the local inhabitants want to get control of the advanced gravity ship. In this case, Trevize literally manages to sleep his way out of this problem, and manage to get out of the planet. From Comporellon, they get the location of Spacer worlds (the first time Spacer worlds are mentioned in the Foundation series).
Next they reach Aurora, the most powerful Spacer world in its time, now a planet without humans and Spacers. They have an adventure here when wild dogs almost manage to pin Trevize down and only Bliss manages to save Trevize by using the power of Gaia.
They next land in Solaria, a world which was the most isolated of the Spacer worlds; with the inhabitants of that time even then refusing to meet each in person, instead meeting only through videographic depiction. The inhabitants have developed a great power called transducer lobes which allows them to channelize natural energy into great use, and live in big estates alone (and are now hermaphrodites, capable of handling reproduction alone). The 3 travelers land in the estate of one of them called Bander, who explains their history and eventually wants to kill them. They only manage to escape when Bliss reluctantly kills Bander (she blocks his energy use and that fries his brain since energy is still coming in but is blocked from going out). They also encounter the young child of Bander, Fallom, who will be killed since she is immature and cannot handle the estate. They manage to escape the robots sent to investigate the death of Bander and take Fallom with them.
They still have a Spacer world to go to, and reach Melpomenia, where they need to wear suits since the atmosphere has long vanished. They find a building with the coordinates of all the spacer world, and also encounter a moss that seems to grow on their suits and manage to kill it by using their blasters and then escape the planet without carrying the moss with them. These coordinates give them a way to find the likely location of Earth since they are able to possibly find the position of Earth at the center of these coordinates.
They next go to a Binary sun system from the above process, and reach a watery planet revolving around a star called Alpha Centauri. The inhabitants are friendly, but they soon discover (through a lady who has had sex with Trevize) that they are being poisoned. They also learn that there was an attempt to restore Earth’s soil (as mentioned in Pebble in the Sky), but it was abandoned. There was also an attempt to terraform the planet of Alpha, but that was also left half way. They also escape from Alpha, but are pretty sure that they are close to Earth now.
And finally they reach the Solar System of Earth, first seeing huge gas giants including one that has large rings around it (just like the legend), and the third planet has a very large satellite. They have found Earth, but Earth is radioactive and does not support any life. They find themselves getting pulled to the Moon, where they eventually find R Daneel Olivaw, who explains that he called them here. He explains the whole history of how he has been guiding the human race for 20,000 years now, including the settling of Alpha Centauri, the creation of psychohistory, the setting up of Gaia. But he is out of time, his brain does not last long and creating a new one does not help. He wants to combine with Fallom, with her long life as a Spacer, it is enough to ensure that Galaxia is setup; Galaxia is the only way to safeguard the Galaxy against aliens from other Galaxies.

Imagine being in a position where you are begged by fans and forced by your publisher to write another book. This book is the sequel to a series that was voted as the Best All-Time Series (a one time award that was never repeated). And the book that you write becomes a bestseller for the first time in your career and wins awards from the industry. This is what happened to Isaac Asimov and the book - Foundation’s Edge. The book was published in 1982 (and since the Second Foundation was published in 1953, this one was a long time in coming). It was much thicker than the first 3 books of the Foundation series and was also a bestseller on the New York times best-seller list (and given that Asimov was a prolific writer, it took a long time for him to reach the best-seller list).

Foundation’s Edge takes the timeline of 500 years after the birth of the Foundation, half-way into the 1000 year period predicted by Hari Seldon for the formation of the next Galactic Empire. The Mule has long been gone, and the distortion introduced in the Seldon Plan by the emergence of the Mule has gone away (due to the careful attention of the Second Foundation). So too has the thought of the Second Foundation, ever since the First Foundation believed it destroyed the agents of the Second Foundation on Terminus.
However, not everyone believes this. The all powerful Mayor of Terminus (and consequently the ruler of the Foundation), Harla Branno, is not sure whether the Second Foundation is truly gone. Similarly, there is a young and impetuous Councilman, Golan Trevize also believes that the Second Foundation exists and is willing to ask this in open Council even though the Mayor is not willing. He has already confided his feelings to another young Councilman Munn Li Compor, who has however disclosed all this to the Mayor. The Mayor is all powerful right now, since there was a opening of the vault and an appearance by Hari Seldon that strengthened her position immensely; she is able to arrest Trevize and send him to exile. She wants him to search for the Second Foundation, while apparently searching for the obscure hidden planet Earth with a older researcher Janov Pelorat. He is given the most advanced ship that the Foundation has, a gravity ship that takes its energy from the gravity forces in space.
Simultaneously, there are more political battles happening in Trantor, the home of the Second Foundation, where 2 upstarts are competing to be the next one to take over as First Speaker, with Stor Gendibal trying to warn about the belief that there is some power stronger than the Second Foundation. In this he is opposed by an opponent Delora Delarmi, who wants to diminish him since that would leave the path clear for her to be the next First Speaker.
In the midst of all this, the entire sequence is actually being guided by the planet of Gaia (Wikipedia), an extraordinary planet where everything is conscious, and part of one. Everything on the planet has one thought, one consciousness, and together the planet wields immense power, even stronger than the Second Foundation. The Gaia concept is also non-threatening in the sense that there is no ambition, but there is a touch of vanity since Gaia believes that the entire Galaxy should be like Gaia, with all elements of the Galaxy being part of one. The reason why Gaia is manipulating everyone is that it wants to bring the situation to a head, and make Trevize decide the future of the Galaxy (he apparently has a very strong intuition, and Gaia wants to him decide whether the future of the Galaxy should be based on the physical power of the First Foundation, or the mental control of the Second Foundation, or the wholeness of Gaia). Whatever decision he makes will be implemented by Gaia.

Isaac Asimov was one of the pioneers of the field of writing about robotics, and was most famous for his creation of the Three Laws of Robotics:
1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
2. A robot must obey orders given to it by human beings, except where such orders would conflict with the First Law.
3. A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
These seem simple enough, but as with laws for humans, there can be many interpretations and conflicts that can arise out of using these laws. ‘The Rest of the Robots’ is a set of 8 short stories that all deal with robots, and many of them also have references to these laws as well as situations arising out of problems with the use of these laws. I found the collection to be very readable and interesting, and considering that most of these stories are more than 50 years old, not dated in any way. We have not had the development of humanoid robotics to the extent that Asimov had written about, so many of these are stories that we will still need to worry about.

The collection was released in 1964, and hence you can consider the book to be a very old book indeed, and yet when I was browsing through some Asimov books on an online bookshop, I found it easily available, which means there is a regular demand for it. The book starts out with a foreword by Asimov in which he explains about how books used to be about robots, they were seen as being part of the Frankenstein complex, where man created robots, and robots would destroy man, and this happened again and again. Asimov chose to move away from this concept, and wrote stories with far more complexity and depth.
The book has 8 short stories:
1. Robot AL-76 goes astray: A story in which a robot bound for the moon somehow manages to get loose on earth, and has to try and figure out its surroundings, especially when it has been fed only information about the moon. It creates a great new machine, but then destroys it when ordered to in mistake. A comedy.
2. Victory international: About projecting the power of robots, especially those constructed with a great deal of care to make extra-strong so that they can impress the ferocious inhabitants of Jupiter.
3. First law: About an exception when the power of the First Law cannot suppress the maternal instincts of a robot, and the robot is willing to let a human die.
4. Let’s get together: A political story about robots being used as terrorists. Showcases one of the biggest fears of humanoid terrorists.
5. Satisfaction guaranteed: One of the most complex stories of this volume. Deals with human emotions such as jealousy, envy and a feeling of low confidence, and how this interfaces with the First law.
6. Risk: About how the human mind can still be a much better instrument to deal with uncertainty and complexity rather than even the most complex positronic brain.
7. Lenny: About the maternal instinct in even the most seemingly hard-boiled scientist can come about when dealing with an under-developed robot.
8. Galley slave: A story which deals with the fear in a human about the advent of robotics and how this could totally destroy human creativity in a slow and gradual way.
The last 4 stories also had the character of Dr. Susan Calvin, whom Asimov used as a representative of the robopshycologist, the head in that area for US Robotics, and a pioneer in the development of robots.