 One problem this approach faces is that it seems to imply that Mary does not really make a new discovery when she says, “So, that is what it is like to experience red.” Upon reflection, however, it is far from obvious that this is really a consequence. For it is widely accepted that concepts or modes of presentation are involved in the individuation of thought-contents, given one sense of the term ‘content’ — the sense in which thought-content is whatever information that-clauses provide that suffices for the purposes of even the most demanding rationalizing explanation. In this sense, what I think, when I think that Cicero was an orator, is not what I think when I think that Tully was an orator. This is precisely why it is possible to discover that Cicero is Tully. The thought that Cicero was an orator differs from the thought that Tully was an orator not at the level of truth-conditions — the same singular proposition is partly constitutive of the content of both — but at the level of concepts or mode of presentation. The one thought exercises the concept Cicero; the other the concept Tully. The concepts have the same reference, but they present the referent in different ways and thus the two thoughts can play different roles in rationalizing explanation.