Synthesized answer
The provided passages do not contain sufficient information to explain the key concepts of Plotinus or Pierre Hadot's work in my own words. The passage only states the title and author of a book, "Plotin ou la Simplicité du regard by Pierre Hadot," and a page number. There are no explanations of concepts, theories, or arguments presented within this excerpt. Therefore, I cannot answer the question about explaining key concepts based on the given material.
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