 It is common to formulate Mary’s new knowledge in terms of Thomas Nagel’s famous locution of knowing what it’s like: Mary does not know (while living in her black-and-white environment) what it is like to see colors and she learns what it is like to see colors only after her release. But this common way to put the point may lead to a confusion of (a) mere acquaintance with kinds of color experiences by having and remembering them and (b) knowledge about what kind of color experience other subjects have at a given occasion, and it may thereby lead to a failure to distinguish two steps of epistemic progress that Jackson’s Mary takes at once. To see the two steps involved one may consider an example used in Nida-Rümelin (1996) and (1998): Like Mary, Marianna first (at t1) lives in a black and white environment. Contrary to Mary (at a later moment t2) she gets acquainted with colors by seeing arbitrarily colored objects (abstract paintings, red chairs, blue tables, etc. but no yellow bananas, no pictures of landscapes with a blue sky etc.). Marianna is therefore unable to relate the kinds of color experiences she now is acquainted with to what she already knew about them at t1. At t2, Marianna may wonder which of four slides (a red, a blue, a green and a yellow slide) appears to her in the color normal people experience when looking at the cloudless sky. At t2 Marianna knows, in a sense, what it is like to have experiences of red, blue, etc. But she still lacks the relevant items of knowledge about what other people experience: there is a clear sense in which she still may not know that the sky appears blue to normal perceivers, she may even have the false belief that it appears to normal perceivers like the red slide appears to her and thus believe, in a sense, that the sky appears red to normal perceivers. Only at t3, when Marianna is finally released and sees the sky, does she gain this item of knowledge. One way to describe the two steps of epistemic progress is this: At t2, by having color experiences, Marianna can form new concepts, she now has what has been called ‘phenomenal concepts’ of kinds of color experiences. By acquiring these concepts she acquires the capacity to ask new questions, and to form new (eventually false) hypotheses (e.g. about the appearance of the sky to normal perceivers). Only at t3 does she acquire the kind of knowledge that the knowledge argument is concerned with (knowledge that involves the application of phenomenal concepts) about experiences of other people.