Carl du Prel

The German philosopher Carl du Prel (1839–1899) was a prominent theoretician and proponent of research into postmortem survival, psychic phenomena and the unconscious mind. He was the most prominent German-language theorist of an individual unconscious mind before Sigmund Freud, who once referred to him as ‘that brilliant mystic’.1 Du Prel was read by psychologists who engaged in psychical research, such as Frederic WH Myers, Carl Gustav Jung, and William James.2 He was also revered by contemporary artists such as the painters Wassily Kandinsky and Hilma af Klint and the poet Rainer Maria Rilke.3

Life and Work

Baron Carl du Prel was born on 3 April 1839 in Landshut, Bavaria, from where his family, who had originated from old Lorraine nobility, moved to Munich shortly after his birth. In 1858, he entered Munich University to study law but joined the Bavarian army two years later, serving as a lieutenant and officer until 1872. In 1868, he received his doctorate in philosophy from the University of Tübingen with a philosophical study of the metaphysical implications of temporal divergences in dreams.4

From 1872, du Prel pursued a career as a freelance writer, publishing articles and essays on philosophy, aesthetics, literature, astronomy, and psychical research, many of which were subsequently compiled in book form.

Du Prel’s philosophical ideas are grounded in Kantian epistemology and the metaphysical systems of Arthur Schopenhauer and Eduard von Hartmann, with whom he corresponded over sixteen years. In his early years he studied the implications of dreams for philosophy and psychology, also astronomy and the works of Darwin, which led to the publication of his first critically acclaimed monograph, a proposal to apply the principles of natural selection to astronomy.5 A later astronomical study, involving epistemological speculations about bodily organization – and thus nature of perception – in hypothetical inhabitants of other planets, eventually led him to acknowledge the logical possibility of supernormal phenomena.6

In 1885, du Prel published his groundbreaking Die Philosophie der Mystik (The Philosophy of Mysticism).7 Earlier he wrote a hiking guidebook for the Alps, Italy, Dalmatia, and Montenegro,8 and a treatise on the psychology of artistic productions,9 the latter of which anticipates crucial elements of his theory of the unconscious mind, later to be presented more systematically in The Philosophy of Mysticism and Die Entdeckung der Seele durch die Geheimwissenschaften (The Discovery of the Soul through the Secret Sciences).10

In 1886, du Prel became a founding member of the Munich Psychological Society, which was modelled on the Society for Psychical Research in England, and which published an important early German psychical research periodical, the journal Sphinx. Other members of the Munich Society were the colonial politician and Theosophist Wilhelm Hübbe-Schleiden, the physician, sexologist and future investigator of physical mediumship Albert von Schrenck-Notzing, and philosopher-psychologist Max Dessoir, who coined the term ‘Parapsychologie’ in a Sphinx article in 1889.11

Hartmann, in an essay on somnambulism, criticized du Prel’s transcendental individualism as presented in the Philosophy of Mysticism.12 Du Prel had launched his philosophical career as a sceptic regarding personal survival, and was considered by Hartmann as an important ally after he published a spirited defence of Hartmann’s philosophy of the unconscious in 1872.13 But a clash between the two followed du Prel’s defence of personal survival and the physical phenomena of spiritualism against Hartmann’s proposal to explain spiritualist phenomena in terms of hallucinations and psychic agency of the living.14 At the heart of the dispute were fundamental disagreements regarding the nature of survival of death: du Prel argued this was personal, while Hartmann, in the vein of Schopenhauer, granted survival in an abstract form only, as a merging of the individual mind into a monistic, inherently unconscious ‘world-substance’.

Hartmann now took sides against his former mentor, as he did also against the Russian Alexander Aksakov, a proponent of the ‘spirit hypothesis’ and founder of the first German psychical research journal, Psychische Studien.15 Aksakov published two volumes containing counter-arguments to Hartmann’s attempt to explain the phenomena of spiritualism in terms of hallucinations and psychic functions of the living.16 When von Hartmann published a reply to Aksakov,17 the latter delegated his response to du Prel,18 which only cemented Hartmann’s estrangement from his former ally.

Du Prel also became known for his edition of Kant’s Vorlesungen über Psychologie (Lectures on Psychology), an obscure collection of post-critical lecture notes first published 17 years after Kant’s death.19 Through his new edition, du Prel hoped to correct the standard image of Kant as a devout critic of occultism. Arguing that Kant’s famous polemic Dreams of a Spirit-Seer20 had been misrepresented as a mere parody of the famed spirit-seer Immanuel Swedenborg, du Prel emphasized certain passages in Kant’s lectures which suggested that Kant had in fact shared crucial insights on the nature of the mind with Swedenborg and subsequently du Prel.

After publishing more books on psychical research, including a ‘hypnotic-spiritistic’ novel,21 Carl du Prel died on 5 August 1899 in Heiligkreuz in Tyrol. He was survived by his children, Hildegard and Gerhard, and his wife Albertine, who later edited a volume with several of du Prel’s articles that had not previously been published in book form.22 Historical research on Carl du Prel became considerably hampered by the complete destruction of his estate during the Second World War.

Du Prel’s ‘Transcendental Psychology’

At the heart of du Prel’s philosophical-psychological system lies the concern that an exclusive focus on every-day waking consciousness misses important insights for philosophy and scientific psychology, and also yields false premises about the nature of mind. As a philosopher, du Prel argued that materialist, Cartesian, and idealist positions were all equally mistaken because they limited definitions of the self to waking consciousness, and thus failed to take into account implications of the unconscious aspects of the mind. Du Prel applauded Eduard von Hartmann’s attempt to remedy this problem, but criticized his pantheistic system for presupposing that the ‘world-substance’ was directly at work in the construction and operation of individual organisms; by contrast, du Prel proposed an intermediating and co-ordinating link between the physical domain and von Hartmann’s impersonal ‘Unconscious’ (which is similar in many respects to Schopenhauer’s ‘World Will’). This link du Prel called the transcendental subject.

According to du Prel, the transcendental subject is the actual metaphysical individual, of which every-day waking self-consciousness is only a pragmatic phenomenological partition, one that emerged as an evolutionary response to the requirements of biological survival. Hence, the transcendental subject is only imperfectly illumined by self-consciousness, but is predicted to teleologically merge with the sphere of the empirical self in the course of evolution. The perceptual dividing line, or epistemological threshold, that is shifting in the course of biological evolution, and which determines the qualities of sensual perception –  and thus the very nature of self-consciousness –  is equated with Gustav T Fechner’s ‘psychophysical threshold’. Du Prel suggested that a shift of the threshold could already be observed and experimentally induced, for example in ordinary sleep, somnambulism and hypnotism. For du Prel, the transcendental subject is the formative agent underlying physiological processes: it is therefore both the thinking and organizing principle in man. Thus, du Prel proposed that the physical and mental alike could be derived from the transcendental subject as a common underlying ‘monistic’ principle.23

Concerning scientific psychology, du Prel argued that experimental psychologists need to study functions and properties of the mind in altered states of consciousness rather than the ordinary waking self alone. This approach was in fundamental contrast with that of Wilhelm Wundt’s and related schools of fledgling academic experimental psychology, which explicitly dismissed altered states of consciousness as a subject of psychological investigation.

Among the relatively uncontroversial areas of research which to du Prel suggested the inherent superiority of the unconscious self to waking consciousness were dreams, spontaneous somnambulism, the appreciation of time in sleep, artistic creativity, and psychopathological phenomena including hysteria and what is now called ‘autoscopy’24.

More exotic phenomena revealing the existence of the transcendental subject, according to du Prel, included hypnotism, somnambulism (sleep-waking and altered states induced by mesmeric passes, a state which du Prel held was different from hypnotic trance), experiences induced by some psychoactive substances, and instances of exceptional memory. Du Prel was also one of the few late nineteenth-century authors to argue for the significance of a study of what is now termed ‘terminal lucidity’ (spontaneous remissions of mental functions in demented and otherwise cognitively impaired terminal patients shortly before death). Moreover, he sought to establish the organizing function of the unconscious mind through the study of ‘phantom limbs’, spontaneous and hypnotically induced vasomotor and other physiological effects (such as the hypnotic production of blisters and other lesions), and maternal impressions (supposed imprints of a pregnant woman’s specific ideas or mental representations on the physique of her unborn child).

Finally, du Prel stressed the scientific importance of the study of debated ‘occult’ phenomena, such as apparitions (of the living and the dead), extra-sensory perception, xenoglossy, and mediumship including spirit materializations. A recurring complaint in du Prel’s writings concerned the habit of most established scientists and academics to dismiss occult and spiritualist phenomena out of hand and without systematic investigation. When du Prel authored the programme for the Munich Psychological Society, for example, he observed: ‘It is clear enough that spiritism will not be banished by mere exclamations of authority from the standpoint of preconceived systems; he who wants to abolish it depends on its investigation just as much as he who wants to promote it’.25

Du Prel argued that since the (pre-existing) transcendental subject was the producer of the body, it followed that it will be unaffected by physical death. For du Prel, postmortem survival was conceived of as an epistemological rather than ontological transformation, for ‘the beyond is the here and now, [only] perceived differently’.26 A study of certain functions of the human psyche (or transcendental subject) suggests that they were adapted to disembodied existence, just ‘as the embryonal formation of the retina has us infer to a life in the world in which the sun shines’.27 Although from about the late 1880s he described himself as a spiritist, du Prel was highly critical regarding specific teachings of spiritualism and identity claims of mediumistic communicators, and he proposed that ‘spiritism is quite dispensable for the problem of immortality; the analysis of the living is sufficient for that purpose’.28

Exemplary for du Prel’s pluralistic methodological approach to then and now understudied functions of the mind was the view that spontaneously occurring phenomena should be corroborated through experimental approaches if possible. Hence, for example, he proposed the use of posthypnotic suggestions in dying volunteers in order to induce – and thus predict – objective postmortem materializations and activities at a given place and time.29

Du Prel often employed ethical arguments as a justification for investigations of occult and related phenomena. Deeply critical of orthodox religion, and mute on the question of theism, he frequently insisted that belief in survival was a necessary condition for altruistic motivation and the cultivation of compassion: ‘It could be demonstrated easily that all social diseases are associated, at their deepest roots, with a generation’s view on death. … In order to be good, which may be an inborn trait, the belief in immortality might be dispensable, but it is indispensable in order to become better’,30 and he held that ‘it is for morality’s sake that the belief in immortality appears desirable in the first place’.31

If survival was a fact of nature, according to du Prel, social interdependence would continue in the afterlife, since spiritual beings depended on mutual support no matter if they were in an incarnate or discarnate state. Du Prel also argued that a common, evidence-based belief in a hereafter and a transcendental world order would help the prevention of suicides, the rise of which he saw as evidence for the pernicious nature of materialist worldviews. Rejecting traditional Christian eschatology with its focus on the notion of supposed divine punishment, du Prel held the only judge of one’s actions was the experience of deep regret over one’s lack of compassion, which he believed may be felt during the awakening of the ordinary self into one’s higher self (or transcendental subject) during some altered states of consciousness and the process of dying.

International Reception and Criticisms

Readers familiar with the ideas of Frederic WH Myers may have noted striking similarities between du Prel’s notion of a ‘transcendental subject’ and Myers’s theory of the ‘subliminal Self’. Both authors embrace a teleological-evolutionary framework for the interpretation of certain properties of the human psyche, such as creativity or extra-sensory perception, which they conceive of as latently pre-existing to their biological conditions of expression. The ‘transcendental subject’ (du Prel) and the ‘subliminal Self’ (Myers), which both authors anticipate will eventually merge with the empirical self in the course of biological evolution, are conceived of as the psychical entity underlying our every-day, empirical, consciousness, and bearer of psychic and psychological functions.

Moreover, the prime concern of both authors was the question of survival, and it is obvious that both employed an integrated methodological approach. That is, rather than through a discussion of evidence directly suggestive of survival alone (such as the data of research into mediumship and apparitions), and with a focus on investigations of understudied functions of the incarnate mind, both du Prel and Myers developed a broad view of the incarnate psyche whose capacity of postmortem survival had a strong a priori plausibility.32

Since du Prel did not read English, and published his key ideas prior to Myers (who did read German), it can be assumed that Myers’s reading of du Prel shaped his ideas rather than the other way around. This is not to say that Myers plagiarized du Prel, however. Myers’s theory of the subliminal Self is far more sophisticated and more thoroughly grounded in contemporary cutting-edge science than du Prel’s model. Moreover, particularly in some of his earlier writings, Myers did occasionally acknowledge his reading of du Prel.33

Initially, du Prel’s work was received with enthusiasm by most fellow German psychical researchers as well as by several figures in the British SPR, but criticisms were voiced increasingly. Albert von Schrenck-Notzing, for example, parted ways with his former teacher because he deemed him to be too uncritical and lacking a rigorously scientific attitude.34

Occasionally, du Prel participated in experiments, investigating mediums like the German Elisabeth Tambke in Munich,35 the Briton William Eglinton in Vienna,36 and, together with Charles Richet, Cesare Lombroso and others, the Italian Eusapia Palladino in Milan.37 However, his philosophical speculations were based mainly on outdated and anecdotal evidence, such as the occult phenomena reported (but insufficiently scrutinized and poorly documented) by previous adherents and practitioners of mesmerism and other authors of historical material enlisted by du Prel. This was a major critique raised by William James and the Oxford philosopher Ferdinand Schiller, both of whom wondered why du Prel did not focus on fresh, contemporary data, particularly the empirical material collected and sifted by the SPR.38 In part, the answer is of course that du Prel, who was fluent in French but did not know English, could not draw on literature he was unable to read.

Du Prel’s somewhat arbitrary terminology did not help his intellectual recognition either. For instance, he often interchangeably employed ‘mysticism’ and ‘spiritism’ as umbrella terms to describe a wide range of occult phenomena that bear no obvious relation to properly mystical experiences (as studied, for example, by William James). Sphinx editor Hübbe-Schleiden once apologized to readers who complained about du Prel’s indiscriminative use of these terms.39

Both du Prel and Myers had a notable impact on the formation of Western ideas of unconscious or subliminal psychology. However, their ideas were rapidly eclipsed in the early twentieth century by adherents of Freud and Jung on the one hand, and on the other, by increasingly reductionistic experimental psychology culminating in Behaviorism. Whereas Myers’s work has begun to be reconstructed by historians of the unconscious mind since Henri Ellenberger’s monumental Discovery of the Unconscious (1970),40 du Prel’s role as a popularizer and theorist of a transcendental depth psychology still awaits systematic appreciation.

Andreas Sommer

Literature

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Aksákow, A.\N. (1890). Animismus und Spiritismus. Versuch einer kritischen Prüfung der mediumistischen Phänomene mit besonderer Berücksichtigung der Hypothesen der Hallucination und des Unbewussten (2 vols.) (G. C. Wittig, Trans.). Leipzig, Germany: Mutze.

du Prel, C. (1869). Oneirokritikon. Der Traum vom Standpunkt des transzendentalen Idealismus. Deutsche Vierteljahrs-Schrift 126, 188-241.

du Prel, C. (1872). Der gesunde Menschenverstand vor den Problemen der Wissenschaft. In Sachen J. C. Fischer contra Eduard von Hartmann. Berlin, Germany: Duncker.

du Prel, C. (1874). Der Kampf ums Dasein am Himmel. Die Darwin’sche Formel nachgewiesen in der Mechanik der Sternenwelt. Berlin, Germany: Denicke.

du Prel, C. (1875). Unter Tannen und Pinien. Wanderungen in den Alpen, Italien, Dalmatien und Montenegro. Berlin, Germany: Denicke.

du Prel, C. (1880a). Die Planetenbewohner und die Nebularhypothese. Neue Studien zur Entwicklungsgeschichte des Weltalls. Leipzig, Germany: Günther.

du Prel, C. (1880b). Psychologie der Lyrik. Beiträge zur Analyse der dichterischen Phantasie. Leipzig, Germany: Günther.

du Prel, C. (1885). Die Philosophie der Mystik. Leipzig, Germany: Günther.

du Prel, C. (1886). Problem: Medium oder Taschenspieler? Der Stand der Streitfrage. Sphinx 1, 363-70.

du Prel, C. (1887). Programm der psychologischen Gesellschaft in München. Sphinx 3, 32-36.

du Prel, C. (1888a). Die monistische Seelenlehre. Ein Beitrag zur Lösung des Menschenrätsels. Leipzig, Germany: Günther.

du Prel, C. (1888b). Die Mystik der alten Griechen. Leipzig, Germany\: Ernst Günther.

du Prel, C. (1889a). Immanuel Kants Vorlesungen über Psychologie. Leipzig, Germany: Ernst Günther.

du Prel, C. (1889b). The Philosophy of Mysticism (2 vols.) (C. C. Massey, Trans.). London: George Redway.

du Prel, C. (1890-91). Studien aus dem Gebiet der Geheimwissenschaften (2 vols). Leipzig, Germany: Friedrich.

du Prel, C. (1891a). Das Kreuz am Ferner. Ein hypnotisch-spiritistischer Roman (2 Vols.). Stuttgart, Germany: J. G. Cotta.

du Prel, C. (1891b). Hartmann contra Aksakow. Psychische Studien 18, 257-74.

du Prel, C. (1892a). Das Rätsel des Menschen. Einleitung in das Studium der Geheimwissenschaften. Leipzig: Philipp Reclam Jr.

du Prel, C. (1892b). Der Kampf um den Spiritismus in Mailand. Psychische Studien 19, 546-66.

du Prel, C. (1893). Der Spiritismus. Leipzig: Philipp Reclam Jr.

du Prel, C. (1894a). Nekromantie in München. Die Zukunft 8, 205-18.

du Prel, C. (1894b). Programm für experimentellen Okkultismus. Sphinx 18, 23-33.

du Prel, C. (1894-95). Die Entdeckung der Seele durch die Geheimwissenschaften (2 vols). Leipzig, Germany: Günther.

du Prel, C. (1899). Die Magie als Naturwissenschaft (2 vols.). Jena, Germany: Costenoble.

du Prel, C. (1901). Der Tod, das Jenseits, das Leben im Jenseits (2nd ed.). Jena, Germany: Costenoble (first ed. 1899).

du Prel, C. (1911). Nachgelassene Schriften. Leipzig, Germany: Max Altmann.

Ellenberger, H.F. (1970). The Discovery of the Unconscious: The History and Evolution of Dynamic Psychiatry. New York: Basic Books.

Freud, S. (2000). Die Traumdeutung. Frankfurt am Main: Fischer Taschenbuch Verlag (reprint of 4th ed., published in 1914).

Gurney, E., Myers, F.W.H., & Podmore, F. (1886). Phantasms of the Living (2 vols.). London: Trübner.

Hartmann, E.v. (1885). Der Spiritismus. Berlin, Germany: Friedrich.

Hartmann, E.v. (1886). Moderne Probleme. Leipzig, Germany: Friedrich.

Hartmann, E.v. (1887). Geister oder Halluzinationen? Sphinx 4, 8-17.

Hartmann, E.v. (1891). Die Geisterhypothese des Spiritismus und seine Phantome. Leipzig, Germany: Friedrich.

Henderson, L.D. (2019). Hilma af Klint and the invisible in her occult and scientific context. In Visionary: On Hilma af Klint and the Spirit of Her Time, ed. by K. Almqvist & L. Belfrage, 71-91, 118-120. Stockholm: Axel and Margaret Ax:son Johnson Foundation.

Hübbe-Schleiden, W. (1889). Bemerkung des Herausgebers. Sphinx 7, 158.

Hübbe-Schleiden, W. (1894). Posthume Suggestionen. Sphinx 18, 33.

James, W. (1894). Review of Cock-Lane and Common Sense by Andrew Lang, and Die Entdeckung der Seele durch die Geheimwissenschaften by Carl du Prel. Psychological Review 1, 630-32.

Kaiser, T. (2008). Zwischen Philosophie und Spiritismus. (Bildwissenschaftliche) Quellen zum Leben und Werk des Carl du Prel. (Ph.D. thesis), University of Lüneburg, Lüneburg, Germany.

Kant, I. (1766). Träume eines Geistersehers, erläutert durch Träume der Metaphysik. Königsberg, Germay: Johann Jacob Kanter.

Kelly, E.F., Kelly, E.W., Crabtree, A., Gauld, A., Grosso, M., & Greyson, B. (2007). Irreducible Mind. Toward a Psychology for the 21st Century. Lanham, Maryland, USA: Rowman & Littlefield.

Kiesewetter, C. (1891). Geschichte des Neueren Occultismus. Geheimwissenschaftliche Systeme von Agrippa von Nettesheym bis zu Carl du Prel. Leipzig, Germany: Friedrich.

Kurzweg, A. (1976). Die Geschichte der Berliner ‘Gesellschaft für Experimental-Psychologie’ mit besonderer Berücksichtigung ihrer Ausgangssituation und des Wirkens von Max Dessoir. (Ph.D. thesis), Freie Universität Berlin, Berlin, West Germany.

Magnusson, G. (2006). Rilke und der Okkultismus. In Metaphysik und Moderne. Von Wilhelm Raabe bis zu Thomas Mann, ed. by A. Blödorn & S.R. Fauth, 144-172. Wuppertal: Arco Wissenschaft.

Mulacz, P. (1976). Der sogenannte wissenschaftliche Spiritismus als parapsychologisches Problem. In Parapsychologie. Ein Handbuch, ed. by O. Schatz, 178-283. Graz, Austria: Styria.

Myers, F.W.H. (1885). Automatic writing. Part II. Proceedings of the Society for Psychical Research 3, 1-63.

Myers, F.W.H. (1886). Further notes on the unconscious self. II. Journal of the Society for Psychical Research 2, 234-43.

Myers, F.W.H. (1903). Human Personality and Its Survival of Bodily Death (2 vols.). London: Longmans, Green and Co.

Schiller, F.C.S. (1894). Review of ‘Die Entdeckung der Seele durch die Geheimwissenschaften’ by Carl du Prel. Philosophical Review 3, 485-90.

Sommer, A. (2009). From astronomy to transcendental Darwinism: Carl du Prel (1839-1899). Journal of Scientific Exploration 23, 59-68.

Sommer, A. (2013a). Crossing the Boundaries of Mind and Body. Psychical Research and the Origins of Modern Psychology. (PhD thesis), University College London, London.

Sommer, A. (2013b). Normalizing the supernormal: The formation of the ‘Gesellschaft für Psychologische Forschung’ (‘Society for Psychological Research’), c. 1886-1890. Journal of the History of the Behavioral Sciences 49, 18-44.

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Treitel, C. (2004). A Science for the Soul. Occultism and the Genesis of the German Modern. Baltimore, Maryland, USA: Johns Hopkins University Press.

Weber, T. P. (2007). Carl du Prel (1839-1899): Explorer of dreams, the soul, and the cosmos. Studies in History and Philosophy of Science 38, 593-604.

Wolffram, H. (2012). Hallucination or materialization? The animism versus spiritism debate in late-19th-century Germany. History of the Human Sciences 25, 45-66.

Endnotes

Footnotes

- 1. Freud (2000, 68n).

- 2. Sommer (2013b, 39). For an initial appreciation of du Prel’s significance in the history of psychology, see Sommer (2013a).

- 3. On contemporary artistic and scientific receptions of du Prel, see, e.g., Kaiser (2008), Treitel (2004), Magnusson (2006), Henderson (2019), Weber (2007), and Sommer (2009), of which this essay is a revised version. For biographical details of du Prel see Kiesewetter (1891), Tischner (1960), and Kaiser (2008).

- 4. Published as du Prel (1869).

- 5. Du Prel (1874).

- 6. Du Prel (1880a).

- 7. Du Prel (1885).

- 8. Du Prel (1875).

- 9. Du Prel (1880b).

- 10. Du Prel (1894-95). Die Philosophie der Mystik was the only monograph by du Prel to appear in an English edition (du Prel, 1889b). The translator was Frederic Myers’s friend CC Massey, who also translated several of du Prel’s articles in the 1880s and 1890s for the British spiritualist periodical Light.

- 11. Other noted members of the Munich Psychological Society were the renowned painters Albert von Keller (1844-1920) and Gabriel von Max (1840-1915). On the Munich Society and similar associations in Germany, see Kurzweg (1976) and Sommer (2013a, 2013b).

- 12. Von Hartmann (1886).

- 13. Du Prel (1872).

- 14. Von Hartmann (1885, 1887). On the debate over hallucinations between Hartmann and du Prel and other psychical researchers, see also Wolffram (2012).

- 15. The journal was launched by Aksakov in 1874 and was continued as Zeitschrift für Parapsychologie from 1926 to 1934. Aksakov (whose name was spelled inconsistently in German publications, ‘Aksákow’ being the most common version) was a Russian Councillor of the State and brother-in-law of the noted chemist and convert to spiritualism, Alexander Butlerov. On the journal Psychische Studien see Sommer (2013c).

- 16. Aksákow (1890). Aksakov proposed three terms describing in his view distinctive categories of phenomena observed in psychical research: Personismus (‘personism’, pertaining to phenomena appearing as if caused by discarnate spirits involving no supernormal information or effect, merely stemming from a medium’s or percipient’s intra-personal unconscious dramatization, as, for example, in most instances of automatic writing); Animismus (‘animism’, describing phenomena appearing as if caused by discarnate spirits, but emerging from unconscious dramatization plus involving psi among the living); and Spiritismus (‘spiritism’, delineating phenomena appearing as if caused by discarnate spirits and suggesting actual postmortem authorship). Aksakov’s tripartite account of psychic phenomena has been used in the terminology of German parapsychology until far into the twentieth century (see, for example, Mulacz, 1976).

- 17. Von Hartmann (1891).

- 18. Du Prel (1891b, 1893).

- 19. Du Prel (1889a).

- 20. Kant (1766).

- 21. Du Prel (1888a, 1888b, 1890-91, 1891a, 1892a, 1894-95, 1899, 1901).

- 22. Du Prel (1911).

- 23. Du Prel (1888a).

- 24. Autoscopy is the clinical term for perceptions of one’s own ‘double’ in cases where the vantage point seems to be located within one’s body. This is in contrast to out-of-body experiences, where one’s physical body is perceived from the vantage point of the mind as presumably located outside the body.

- 25. Du Prel (1887), 36. Translations from the German are mine.

- 26. Du Prel (1901), 73.

- 27. Du Prel (1888a), 306.

- 28. Du Prel (1888a) 320. Du Prel did not distinguish between survival, which may not necessarily be eternal, and immortality proper.

- 29. Du Prel (1894b). Perhaps understandably, this proposal provoked ethical concerns, e.g. from Hübbe-Schleiden (1894).

- 30. Du Prel (1888a), 309.

- 31. Du Prel (1901), 63.

- 32. For a full exposure of Myers’s ideas see his posthumously published magnum opus (Myers, 1903), and Kelly et al. (2007).

- 33. See, for instance, Myers (1885), 27; (1886), 240), Gurney, Myers, & Podmore (1886), vol. 1, 231n1.

- 34. This lead to a chasm within the Munich Psychological Society, which was co-founded by du Prel and young Schrenck-Notzing (Sommer, 2013b).

- 35. Du Prel (1894a).

- 36. Du Prel (1886).

- 37. Du Prel (1892b, 1893), Aksakof et al. (1893).

- 38. James (1894), Schiller (1894).

- 39. Hübbe-Schleiden (1889).

- 40. Ellenberger (1970).

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