 At the same time, Condillac made clear that after the fall of the first man and woman the soul has become dependent on the body: the building blocks of mental life, sensations, are occasioned by various physical motions caused by the external objects affecting the senses and the nervous system (Essay I.i.1 §8). If higher cognitive functions are ultimately to be explained merely in terms of transformations of sensations, then Condillac was left with the problem of showing the precise line of demarcation between humans and other animals. Two solutions to this problem were foreclosed to Condillac. One possible solution was the view of Aristotle: the human soul is characterized by a higher rational part in addition to the vegetative and animal parts (the vegetative part being responsible for nutrition and growth, and the animal part being responsible for sensation and motion). Condillac’s sensism argued precisely against this essentialist view of the difference between higher and lower cognitive functions and by extension against the essentialist view of the difference between humans and animals. The second solution, which in Condillac’s times was proposed by Buffon in his Natural History (1749-53), was the Cartesian hypothesis of a mechanical soul. According to Descartes, only the rational soul is responsible for consciousness. Animals, being devoid of this kind of soul, are mere machines and thus incapable of being conscious. Condillac, on his part, was rather inclined to endorse the common-sense view that makes animals capable of sensation and thus of consciousness.