The third property of the serpent is that if a man attacks it, it exposes its whole body but protects its head. The interpretation is that one should allow the body to be destroyed in martyrdom in order to protect the "head" of Christian faith. This property of the serpent, if it appears at all, is usually listed last.
The serpent in the van der Borcht copperplate engraving below is protecting its head in the coils of its body.
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The woodcut below (from the Rome, 1577 edition) is essentially the same as the van der Borcht engraving.
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Second property of the Serpent
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