Synthesized answer
The provided passages do not contain enough information to fully answer the question about the central thesis of "Plotin ou la Simplicité du regard."
The passages only indicate the title of the book and its author, Pierre Hadot [194]. There is no content describing Plotinus or the ideas presented in Hadot's work. Therefore, the central thesis of the text cannot be determined from this information.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Plotin ou la Simplicité du regard by Pierre Hadot Pages: 194