The relationship between Wittgenstein's personal beliefs and his philosophical views is considerably closer than normally is the case with philosophers, especially analytic philosophers. In Wittgenstein's case we know that his personal values were intimately related to his philosophizing and even exactly when his personal and his philosophical concerns began to overlap in ways that have to be taken seriously. In 1916 he writes, “Colossal strain in the last month. Have reflected much about everything but curiously incapable of producing the connection with my mathematical trains of thought. However, the connection will be produced! What cannot be said cannot be said!” (GT, 6–7.VII,16) It seems that he had attained clarity about his problems relating to logic and now was challenged to apply the same approach that had been fruitful in logic to his existential problems: those problems must “dissolve” of themselves on the basis of an alternative mode of formulating them (GT, 26.XI,14; and see CV, 27). It is precisely at the point where Wittgenstein begins to “produce” that connection, as we shall see, that Otto Weininger started to become philosophically important to him. What is more, it is precisely here that the points of contact between Wittgenstein and so-called “Continental philosophers” such as Friedrich Nietzsche, Søren Kierkegaard, and Martin Heidegger emerge.

Wittgenstein was surely aware of Weininger long before the section from Über die letzten Dinge called “Animal Psychology” came to play a crucial role in his own understanding of the ethical implications of his elimination of logical theory in the Tractatus.