Most Swiss restaurants and pubs have an emblem hanging outside the entrance.
Usually, these have some sort of iconographic significance or relate to an animal.
They come from a time when icons were far more important than words.
People were told to meet at the Adler; to follow such instructions did not require the ability to read.
The symbol was hanging there.

Notice that the fish has been hooked and that the fish line is made of a spider's silk.

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