The same drawing flips between a duck and a rabbit depending how you see it

Ludwig Wittgenstein used an old ambiguous drawing — readable as either a duck or a rabbit, never both at once — to argue that 'seeing' isn't just passively receiving an image. You can look at identical lines on a page and genuinely see something different depending on what you bring to the looking, which he called 'seeing as'. For Wittgenstein this wasn't a party trick: it showed perception and interpretation are tangled together in ways a simple picture-in-the-eye model of vision can't explain.

— Ludwig Wittgenstein, Philosophical Investigations — Part II, section xi, 1953 (published posthumously)
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