There are a few things I may have missed in this post. One is that, as was discussed in class, the Greeks of Plato’s time did not have the sort of atomized concept of the self that we have now. That is, I might think of my self as internal and absolutely me. Where as my participation in, for instance, a philosophy class is merely something I do, something inessential that does not really affect my essence. The Greek view, as far as I understand it, is that my role in the world in inextricable from my self. So, lighting up cigars in class would not be seen as merely something that gives me pleasure and everyone else pain, but as something that makes me a bad student and citizen, and thus also causes me pain. The adequacy of the seemingly purely physical conception of pleasure and pain that Socrates seems to advocate in the Protagoras is still a question, though.