The The Physiologus reference article from the English Wikipedia on 24-Apr-2004
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The Physiologus

The Physiologus was a predecessor of bestiaries (books of beasts).

It consisted of descriptions animals, birds, fantastic creatures; sometimes stones and plants, often with moral content.

The Physiologus was compiled in Alexandria in the 2nd century AD, was translated into most Christian languages retaining its influence over people's minds in Europe for over a thousand years.