All animals were considered as automata--that is, as self-acting machines, moved by a something called instinct, for want of a better name.

To talk about the souls of animals or the spirits of animals would have been very dangerous in the Middle Ages, when the Church had supreme power; it would indeed have been to risk or to invite an accusation of witchcraft, for demons were then thought to take the shape of animals at certain times.

To discuss the _mind_ of an animal would have been for the Christian faith to throw doubt upon the existence of human souls as taught by the Church; for if you grant that animals are able to think, then you must acknowledge that man is able to think without a soul, or you must acknowledge that the soul is not the essential principle of thought and action.

Until after the time of Descartes, who later argued philosophically that animals were only machines, it was scarcely possible to argue rationally about the matter in Europe.
Nevertheless, we shall soon perceive that this explanation will not cover all the facts.

You will naturally ask how it happens that, if the question be a question of animal souls, birds, horses, dogs, cats, and many other animals have been made the subject of Western poems from ancient times.
The silence is only upon the subject of insects.