To understand the medieval mentality it is first of all necessary to understand the hereafter, and in the Middle Ages the hereafter was mainly occupied by Hell. Hell is a devouring and hostile animal power, usually pictured as the throat of the Leviathan, the monster opening his jaws to swallow the damned.

And among the damned writhing in flames or boiling in cauldrons, next to the miser with the purse around his neck and to the lust bitten at her bosom by snakes and toads, kings and bishops can often be recognized. In Hell vice and disorder rule.
A human or animal body horned, clawed or in the guise of a monk, that is the way the Devil has been pictured over the centuries. A blue angel; this way it was pictured by Christian iconography. “A fallen angel”; blue because, according to the ancient interpretation of colours, in opposition of red which meant light and fire, blue was the symbol of air and darkness, the retreat of evil spirits. Famous is the 6^th century mosaic in the church of St. Apollinare Nuovo in Ravenna showing Evangelist Matthew’s parable, in which a blue angel is pictured on the left of the judging Christ while separating sheep from kids
Since the 12th century the Devil took a new shape, that of a  “satyr”, pictured still nowadays in the west of the world: a manlike creature with horns, tail, clogs and claws.  Claws represented the Devil’s habit of clutching and gripping souls tight.

In the Middle Ages he was often pictured with another face on his belly, and this second face was spread in various representations involving several parts of his body, such as sex, breast and articulations. The Devil’s monstrousness and bestiality are strengthened by moving his head, the seat of intelligence, to the “obscene” parts of his body. In the fourteenth century a new image appear, the “tempting devil” who, disguised in a devote way to mask his monstrosity, attempts to confuse people, but a careful observer cannot avoid seeing those devilish characteristics which cannot be hidden, that is, his claws and his tails. In the Middle Ages the picture of a four-legged demon also appears.

The Cat.

Associated with the woman, he is thought of as greedy and thief, vain and lascivious.
Cat, woman and devil, a mental association to define a witch.
And, as well as the witch, the cat is burnt on the stake by crowds of fanatics.

In 1344, on the so called “Cat Wednesday” during the Lent in Metz, thirteen cats were closed in an iron cage and left burn. That custom spread over several European towns. On the Ash Wednesday a stake would be raised on the square, upon where a basket full of cats was hung through a rope and slowly lowered into flames.
From the bonfires torches were lit and during the procession trees, animals and grass were skimmed as a wish of happiness.
The Middle Ages, a time of obscure beliefs and unheard-of violence.

The Last Judgement by  Beato Angelico