A good read, and apart from the 3 laws for robots, I now realise there was also a 4th law:

Zeroth Law is: ‘A robot may not injure humanity or, through inaction, allow humanity to come to harm.’ This automatically means that the First Law must be modified to be: ‘A robot may not injure a human being, or, through inaction, allow a human being to come to harm, except where that would conflict with the Zeroth Law.’ And similar modifications must be made in the Second and Third Laws.”

But this book also answered many questions and also revealed a plan that is older than Seldon’s Plan…