This is an odd and unsatisfying book. It's barely a novel at all - very little happens, and almost all of it is in dialogue, or more accurately a sequence of extended monologues. The doctor of the title embodies an ideal character for Balzac, an enlightened social reformer who changes the fortunes of a remote French village through the application of industrial techniques and elementary economic knowledge. The first third of the book is a monologue by the doctor explaining how he achieved this.
A long middle section is another monologue recounting much of Napoleon's rule. Balzac was an overt Bonapartist, and his belief in the virtues of strong leadership, as opposed to weak democracy, are voiced by an old soldier.
The book has the feel of a transcription of Balzac's own excited conversations - it's very readable in parts, but doesn't cohere into a narrative. It has many of his virtues - his energy and engagement - but it's too transparently a political lecture to have dramatic strength. An amusing diversion.