In 1919, just prior to the publication of Psychological Types, Jung sent a letter to Sabina Spielrein detailing the psychological types of the following people:
Eugen Bleuler: E-TJ type
Sabina Spielrein: Extrovert
Jung on Schiller: Both IN-J and INTP?
Update Februrary 2013: As suggested by the excellent comments of the user ‘Jungster’ below, it seems that Jung identifies Schiller as an INTP in Psychological Types and not as an INJ with introverted thinking (i.e. an INFJ) as we had first understood. This then makes the case for Jung identifying Schiller as INJ in 1919 and INTP in 1921. Of course, there is nothing wrong with revising one’s views, but since Jung is a figure of such seminal historical importance, we feel obliged to chronicle it to the best of our ability. See the comments for more.
In 1919, Jung writes: “Bleuler and Freud are extravert. Nietzsche and Jung introvert. Goethe is intuitive and extravert. Schiller is intuitive and introvert.” published in Sabina Spielrein: Forgotten Pioneer of Psychoanalysis p. 58 Of course, the case can be made that Jung is simply saying that Schiller is some blend of introvert with strong intuition, but it seems unlikely, given the primitive state of typology at this point.
In 1921, Jung writes in Psychological Types §104:
“I consider that Schiller … corresponds to the introverted type, the question next arises as to which subdivision he belongs. This is hard to answer. Without doubt intuition plays a great role with him; we might on this account, or if we regard him exclusively as a poet, reckon him an intuitive. But in the letters on the aesthetic education of man it is unquestionably Schiller the thinker who confronts us. Not only from these, but from his own repeated admissions, we know how strong the reflective element was in Schiller. Consequently we must shift his intuitiveness very much towards the side of thinking, thus approaching him also from the angle of the psychology of the introverted thinking type.”
Thus seeming to identify Schiller as an INTP.
Jung also left Sabina Spielrein three diagrams on type, as included below: