"Kaninchen und Ente" ("Rabbit and Duck"), the earliest known version of the <a href="https://en.wikipedia.org/wiki/Rabbit%E2%80%93duck_illusion" class="extiw" title="w:Rabbit–duck illusion">duck–rabbit illusion</a>, from the 23 October 1892 issue of <i><a href="https://en.wikipedia.org/wiki/Fliegende_Bl%C3%A4tter" class="extiw" title="w:Fliegende Blätter">Fliegende Blätter</a></i> (<a rel="nofollow" class="external free" href="http://diglit.ub.uni-heidelberg.de/diglit/fb97/0147?sid=8af6d821538a1926abf44c9a95c40951&amp;zoomlevel=2">http://diglit.ub.uni-heidelberg.de/diglit/fb97/0147?sid=8af6d821538a1926abf44c9a95c40951&amp;zoomlevel=2</a>). It is captioned, "Welche Thiere gleichen einander am meisten?" ("Which animals are
most like each other?")
<p>Unknown artist<span style="display: none;">Unknown artist</span> 
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<table class="layouttemplate" style="margin: 0.5em auto; width: 100%; background-color: #f8f8f8; border: 2px solid #e0e0e0; padding: 5px;" lang="en" dir="ltr"><tbody><tr><td style="padding:5px;"><div class="wpImageAnnotatorControl wpImageAnnotatorOff"><a href="//commons.wikimedia.org/wiki/File:Applications-graphics.svg" class="image"><img alt="Applications-graphics.svg" src="https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Applications-graphics.svg/45px-Applications-graphics.svg.png" decoding="async" width="45" height="45" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Applications-graphics.svg/68px-Applications-graphics.svg.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Applications-graphics.svg/90px-Applications-graphics.svg.png 2x" data-file-width="48" data-file-height="48"></a></div>
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<td style="width:100%;">This  is a <i><b><a href="https://en.wikipedia.org/wiki/Image_editing" class="extiw" title="w:Image editing">retouched picture</a></b></i>, which means that it has been digitally altered from its original version.
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Vectorized using Inkscape 0.92.3 from <a href="//commons.wikimedia.org/wiki/File:Kaninchen_und_Ente.png" title="File:Kaninchen und Ente.png">Kaninchen_und_Ente.png</a>, itself a high-resolution scan from scanned page of <i>Fliegende Blätter</i>, full page: <a href="//commons.wikimedia.org/wiki/File:Flegende-Blatter-1892.png" title="File:Flegende-Blatter-1892.png">Flegende-Blatter-1892.png</a>