We know that Wittgenstein had a high opinion of Weininger. What we do not know is what his opinion rested on. It is extremely difficult to identify passages in his writings where a clearly Weiningerian thought is discussed; but that may be for the reason that there is no such thing as a clearly Weiningerian thought. All attempts to clarify the relation between Weininger and Wittgenstein face a number of difficulties. Wittgenstein's philosophy is generally seen as firmly anchored in, or forming part of the foundations of, the analytic tradition, and the name of Weininger – a thinker who is evidently remote from this tradition – is unlikely to crop up in this context. If, on the other hand, a reader happens to come across Weininger in connection with other figures associated with fin-de-siècle Vienna, he is unlikely to know enough about Wittgenstein's philosophy to make much of the fact that Wittgenstein thought highly of Weininger.

Weininger's world, the Vienna of his and the young Wittgenstein's day, is far removed from us and the styles of thinking we are familiar with. Of course, we are often told that many products of that time go to form essential parts of what we still tend to regard as our culture: there is the music of Gustav Mahler and the second Viennese school –Schönberg, Berg, Webern; there are the frequently exhibited and reproduced paintings of Klimt, Schiele, and Kokoschka, the admired architectural designs and buildings by Otto Wagner and Adolf Loos; there are highly recommended and much anthologized writings by Hugo von Hofmannsthal, Arthur Schnitzler, and Stefan Zweig; there is Karl Kraus, who read and defended Weininger; and there is Freud, who felt compelled to distance himself from Weininger and his ideas.