 In sum, Pereira thought that all these movements might be explained by turning to two types of causes: specific causes and generic causes. The first ones consist of various actions of the species on the receptive organs; that is to say, environmental stimulation. Generic causes are the functional interest. Pereira placed these causes under the general term “nature”, which plays a role as a universal regulator (AM: I.349). This broad generic cause is responsible for animals having organs adequate to enable them to interact with their habitat. This also explains the different bodies and types of animals and their varying capacity to be trained. Nature is also responsible for the fact that some of an animal’s external movements serve as signs. For instance, a dog’s bark or a lion’s roar frightens us and warns us of possible attack. Pereira considered instinctive movements to include those basic processes related to environmental adaption, especially the search for food, avoiding danger, etc. These movements are the result of the interaction between natural tendencies in the animal and concrete environmental circumstances. In this way, Pereira explained the perfect harmony between the beast and its physical, animal, and human surroundings (see Bandré &amp; Llavona 1992: 163–164).