Man's superiority to the brute depends on the greater perfection of his sense of touch; on the greater variety of his wants and his associations of ideas; on the idea of death, which leads him to seek not merely the avoidance of pain but also self-preservation; and the possession of language. Without denomination no abstractions, no thought, no handing down of knowledge. Although all that is mental has its origin, in the last analysis, in simple sensations, its development requires emancipation from the sensuous, and language is the means for freeing ourselves from the pressure of sensations by the generalization and combination of ideas. A more moderate representative of sensationalism was Charles Bonnet, who later exercised a considerable influence in Germany, especially until Tetens (1720-93; _Essay in Psychology, or Considerations on the Operations of the Soul_, 1755; _Analytical Essay on the Faculties of the Soul_, 1760; _Philosophical Palingenesis, or Ideas on the Past and the Future of Living Beings_, 1769, including a defense of Christianity; _Collected Works_, 1779). Sensations, to which he, too, reduces all mental life, are, in his view, reactions of the immaterial soul to sense stimuli, which operate merely as occasional causes. On the other hand, he emphasizes more strongly than Condillac the dependence of psychical phenomena on physiological conditions, and endeavors to show definite brain vibrations as the basis not only of habit, memory, and the association of ideas, but also of the higher mental operations. In harmony with these views he adheres to determinism, and finds the motive of all endeavor: in self-love, and its ultimate aim in happiness. To the latter the hope of immortality is indispensable. The link between Bonnet's theory of the thoroughgoing dependence of the soul on the body and his orthodox convictions, is formed by his idea of an imperishable ethereal body, which enables the soul in the life to come to remember its life on earth and, after the dissolution of the present material body, to acquire a new one. Animals as well as men share in the continuance of existence and the transition to a higher stage. The material earnestness of these thinkers is in sharp contrast to the superficial and frivolous manner in which Helvetius (1715-71) carries out sensationalism in the sphere of ethics. His chief work, _On Mind_, came out in 1758; and a year after his death, the work _On Man, his Intellectual Faculties and his Education_. The search for pleasure or self-love is, as Helvetius thinks he has discovered for the first time,[1] the only motive of action; the laws of interest reign in the moral world as the laws of motion in the physical world; justice and love for our neighbors are based on utility; we seek friends in order to be amused, aided, and, in misfortune, compassionated by them; the philanthropist and the monster both seek only their own pleasure.