5.511 How can the all-embracing, world-mirroring logic use such special hooks and manipulations? Only by all these being connected into [i.e. so as to form] one infinitely fine network, the great mirror.

What hooks and manipulations? I don’t know. But the last sentence must be ironical, surely. My parenthetical comment on its meaning follows p. 61 of Letters to Ogden. Bearn (p. 63) connects the talk of a “great mirror” here with Tolstoy’s claim in his The Gospel in Brief, that, in Bearn’s words, “The key to what Tolstoy calls peace, joy, and security is to renounce one’s personal desires and make one’s own will a great mirror of the will of God.” I don’t find this convincing. See also 6.13.

Friedlander (p. 93, note 4) notes Schopenhauer’s reference to a mirror of the world (WWR, vol. 1, pp. 287-288): “Man … is the most complete phenomenon of the will, and, as was shown in the second book, in order to exist, this phenomenon had to be illuminated by so high a degree of knowledge that even a perfectly adequate repetition of the inner nature of the world under the form of representation became possible in it. This is the apprehension of the Ideas, the pure mirror of the world.” Friedlander takes the ideas to be mirrors, but it seems more natural to read this passage as calling man’s apprehension of the Ideas the mirror of the world, doesn’t it? This is borne out by p. 206 of vol. 2, where Schopenhauer writes of “the knowing part of consciousness” becoming “the clear mirror of the world.” Cf. p. 216 and p. 380. The intellect is the mirror of the world, for Schopenhauer.

Black (p. 27) calls this image of a mirror the dominant image of the whole book.

See also Schopenhauer Fourfold Root p. 151: “What is properly called thinking in the narrower sense is the occupation of the intellect with concepts, the presence in our consciousness of that class of representations here considered. It is also expressed by the word reflection which, as a metaphor from optics, at the same time states the derived and secondary character of this kind of knowledge.” This ability, Schopenhauer says, is what places us above the animals. P. 153: “All thinking in the wider sense, and hence all inner activity of the mind generally requires either words or pictures of the imagination; without the one or the other it has no support.”

Black (p. 277) says cf. 4.121. He notes that Anscombe identifies the great mirror with language on p. 164 of her Introduction.

There are 42 entries under “mirror” in the index to Schopenhauer’s The World as Will and Representation.