which is the result of the vocal organs producing sound waves. Third, language (not visible in the picture), with its rules, arises from the speech circuit socially and historically as a non-physical phenomenon. However, Saussure considers it "concrete" and not an abstraction, making language the suitable subject of linguistics as a natural science. The rules of language are gradually learned by the child, but adult perceptions of language vary to some degree. Saussure explains that "Among all the individuals that are linked together by speech, some sort of average will be set up : all will reproduce—not exactly of course, but approximately—the same signs united with the same concepts." Beginning with the Greek word semîon meaning "sign", Saussure proposes a new science of semiology: "a science that studies the life of signs within society". However, based on William Dwight Whitney's The Life and Growth of Language (1875), Saussure emphasizes that the concept of 'life' is in this context metaphorical and not biological. Saussure does not engage in the research of any other signs than linguistic ones, but the idea of social interaction being based on sign systems was later extensively exploited by the structuralists. Cultural historian Egbert Klautke notes that Saussure borrowed his language-versus-speech distinction from his teacher Heymann Steinthal, who proposed Völkerpsychologie. In this concept, language is a part of the spirit of the nation or Volksgeist. Saussure advocates the commonly accepted view of his time. This collectivist view became later known as the standard social science model (SSSM), thus also representing the most common understanding of culture in contemporary sociology. What is special in Saussure's treatise is his theory that social behavior is symbolic or semiological, consisting of socially regulated combinations of signs. Based on the Course, linguistics is a sub-field of social and cultural studies, and these belong to the sphere of semiology, the study of sign-systems. Semiology itself is a type of systems theory. Saussure explains further that language arises as a well-defined homogeneous object from the heterogeneous mass of speech facts. Speech is many-sided and heterogeneous because it belongs partly to the individual. Language is a self-contained whole: it is fully social and cannot be changed by the individual. Language is not complete in any speaker: it is a product that is passively assimilated by the individual. It exists only within a collective. Language is "a system of signs that express ideas". Through the interaction