 To avoid such undesirable consequences, which de facto put animals in the same category as human beings, Pereira tried out an alternative explanation of animal behavior. This behavior and the diversity of movements observed in animals is due to what he called some occultae qualitates by which visual images (species) coming from outside, or certain affections that occur in the phantasmata that stay in the front of the brain (occiput) set the animal in motion by activating its nervous system (AM: I.253). In the case of human beings, who, like animals, are also exposed to these species and have inside their brains the same phantasmata, there is a real mental activity which is able to generate their own movements through the knowledge of the object.