This chapter first reviews Wittgenstein's distinction between use of 'I' "as subject" and use of 'I' "as object" in the Blue book. Then, it explains what Immanuel Kant meant by "consciousness of oneself as subject". The chapter argues that Kant's notion offers resources for understanding a heretofore unexplored aspect of the use of 'I' as subject. The chapter offers empirical-psychological support for the distinctions, and for the dependence relation suggested between the different kinds of self-consciousness grounding the uses of 'I' as subject. It draws on a clinical example borrowed from Oliver Sacks in his book The Man who Mistook his Wife for a Hat to illustrate the relation between the two quite different uses of 'I' as subject and the two corresponding kinds of immunity to error through misidentification (IEM) relative to the first-person pronoun analyzed in the first two parts of the chapter.