I'm on book 2 now and I've been really interested in it. The main conceit is that this psychologist came up with a theory called "psycho history" which allows him to predict the future more or less by considering material conditions and the psychology of large groups of people and extrapolating from that what the most likely course of history will be. Maybe it's just because I read it after binging theory but it sounds a lot like he just came up with dialectical materialism, although it's used in a fantastical way in the novels.
I read the entire series (original trilogy + the two sequels written by Asimov decades later) and I enjoyed it thoroughly. Without spoiling anything, books 4 and 5 are really different from the preceding three, so much so that they don't even feel like part of the same saga.
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And I swear the 5th's ending legit scared me for days, even if it's not the intented reaction.