 Pereira’s nominalist position rests on this basis. The question of whether universals are or not substances is elucidated by explaining the universal concept as a connotative term which exists only in the sentences formulated by our own mind. The soul understands that the singular elements that can constitute a genus or a species have similar characteristics, and thus it regards them all as a unity and this unity as a universal concept. Applying this doctrine, Pereira directed his criticism to certain metaphysical concepts that were meaningless and unnecessary for him. Such is the case, for example, of the scholastic difference between essence and existence. Against St. Thomas, he affirmed that these two concepts are not different realiter but only conceptually, and this because 