and English empiricism (sensualism) – was made clear in his book Beiträge zur Theorie der Sinneswahrnehmung (Contributions on the Theory of Sensory Perception) published in 1862, by his use of a quotation from Gottfried Wilhelm Leibniz on the title page: "Nihil est in intellectu quod non fuerit in sensu, nisi intellectu ipse." (Leibniz, Nouveaux essais, 1765, Livre II, Des Idées, Chapitre 1, § 6). – Nothing is in the intellect that was not first in the senses, except the intellect itself. Principles that are not present in sensory impressions can be recognised in human perception and consciousness: logical inferences, categories of thought, the principle of causality, the principle of purpose (teleology), the principle of emergence and other epistemological principles. Wundt's most important books are: Lehrbuch der Physiologie des Menschen (Textbook of Human Physiology) (1864/1865, 4th ed. 1878); Grundzüge der physiologischen Psychologie (Principles of Physiological Psychology), (1874; 6th ed. 1908–1911, 3 Vols.); System der Philosophie (System of Philosophy), (1889; 4th ed. 1919, 2 Vols.); Logik. Eine Untersuchung der Prinzipien der Erkenntnis und der Methoden wissenschaftlicher Forschung (Logic. An investigation into the principles of knowledge and the methods of scientific research), (1880–1883; 4th ed. 1919–1921, 3 Vols.); Ethik (Ethics), (1886; 3rd ed. 1903, 2 Vols.); Völkerpsychologie. Eine Untersuchung der Entwicklungsgesetze von Sprache, Mythos und Sitte (Cultural Psychology. An investigation into developmental laws of language, myth, and conduct), (1900–1920, 10 Vols.); Grundriss der Psychologie (Outline of Psychology), (1896; 14th ed. 1920). These 22 volumes cover an immense variety of topics. On examination of the complete works, however, a close relationship between Wundt's theoretical psychology, epistemology and methodology can be seen. English translations are only available for the best-known works: Principles of physiological Psychology (only the single-volume 1st ed. of 1874) and Ethics (also only 1st ed. of 1886). Wundt's work remains largely inaccessible without advanced knowledge of German. Its reception, therefore, is still greatly hampered by misunderstandings, stereotypes and superficial judgements. Central themes in Wundt's work Memory Wilhelm Wundt conducted experiments on memory, which would be considered today as iconic memory, short-term memory, and enactment and generation effects. Process theory Psychology is interested in the current process, i.e. the mental changes and functional relationships between perception, cognition, emotion, and volition/ motivation. Mental (psychological) phenomena are changing processes of consciousness. They can only be determined as an actuality, an "immediate reality of an event in the psychological experience". The relationships of consciousness, i.e. the