HISTORY: BEFORE THE INFERENCE REVOLUTION Aristotle set forth the three principles-temporal and spatial contiguity, similarity, and contrast-that state the conditions under which ideas are associated in memory. He is the father of associationism, which flowered again in the 17th-19th centuries with the British school of Thomas Hobbes, John Locke, David Hume, David Hartley, James Mill and others. Ideas and sensations were the elements of the mind: sensations were the elements of sensory experience; ideas, those of nonsensory, higher mental processes such as thought; and ideas were composed from sensations. Associationism provided the framework for the emerging experimental psychology of the late 19th century. However, Wilhelm Wundt, the father of experimental psychology, believed that the experimental method should be limited to the study of simple psychical processes, that higher mental processes must be approached by different methods, as in his Vòlkerpsychologie (cultural psychology). Wundt (1897) argued that since thought processes are as variable as they are and gain a degree of constancy only when they become collective, their study is the subject matter of social psychology. The experimental method cannot decompose human thinking, which is strongly dependent on language and culture.