I probably shouldn't have led with "absence of pain".... I did so knowing that it's a hot-button issue here, and hoping to demonstrate that he presented an interesting view of it.
Having said that, Guyau does make an emphatic case against "absence of pain." Where I get uncomfortable (in a good way
) is with his narrowing the goal to a single focus of serenity. However, and I think Don might have something to say about this, it's not wrong to pursue serenity. Especially if you're thinking of it as homeostasis. A singular focus on serenity may not be correct, but serenity allows for maximal appreciation of a variety of pleasures. I think Epicurus repeatedly makes the latter point.
Part of what's interesting to me is that Guyau wrote in French (which I don't speak) and naturally interpreted some of the tricky Greek words differently than we might. At the same time, much of what he wrote aligns well with my current understanding. Reading this book is making me think deeper, and in a new way, about a variety of ideas.