A bird with a terrible voice and flesh too hard to cook
The flesh of the peacock is so hard that it does not rot, and can hardly be cooked in fire or digested by the liver. Its voice is terrible, causing fear in the listener when the bird unexpectedly begins to cry out. Its head is like a snake, its breast is sapphire colored, it has red feathers in its wings, and has a long green tail adorned with eyes. If it receives praise for its beauty, it raises its tail, leaving its rear parts bare. When it suddenly awakes it cries out, because it thinks its beauty has been lost. It is a bird with great foresight. Its feet are very ugly, so the peacock refuses to fly high in order to keep its feet hidden.
The hard flesh of the peacock represents the minds of teachers, who remain unaffected by the flames of lust. The fearful voice of the peacock is like the voice of the preacher who warns sinners of their end in hell. The "eyes" on the peacock's tail are to signify the ability of the teachers to foresee the danger we all face in the end. The raising of the peacock's tail when it is praised should remind us to not let pride from praise affect us, so we do not expose our ugly vanity.
The Aberdeen Bestiary, following a biblical quote saying that Solomon sent expeditions to bring back peacocks, has a two page sermon on the allegorical meaning of this theme.