The fox is a crafty and deceitful animal that never runs in a straight line, but only in circles. When it wants to catch birds to eat, the fox rolls in red mud so that it appears to be covered in blood. It then lies apparently lifeless; birds, deceived by the appearance of blood and thinking the fox to be dead, land on it and are immediately devoured.

The most famous fox of the Middle Ages was Reynard, the trickster hero of the Romance of Reynard the Fox.

The fox represents the devil, who pretends to be dead to those who retain their worldly ways, and only reveals himself when he has them in his jaws. To those with perfect faith, the devil is truly dead.

The most common fox illustration show the story of the fox luring birds by pretending to be dead. Several kinds of birds are shown descending on the "corpse" (magpies are common), often with one putting its head in the fox's mouth to get its tongue.

The fat and marrow of a fox is a treatment for the shrinking of sinews. It blood softens hard things and is therefore useful for breaking up bladder stones. A fox tongue in a ring or bracelet will protect the one wearing it from blindness.

Says Thomas of Cantimpré: Its liver, roasted and drunk with wine, cures iliac affections. Its heart is capable of stopping the flow of blood; the liver likewise. Its brain, given to children, often permanently frees them from epilepsy. Its fat is good for all pains in the limbs. Its spleen also dissolves contracted organs. If the flesh of a fox is burnt, its dust is worth taking with wine for asthmatics.