Many of
the Ancients' writings would have been lost without the efforts of Muslim, Christian, and Jewish translators in the
House of Wisdom, the
House of Knowledge, and other such institutions in the
Islamic Golden Age, whose glosses and commentaries were later translated into
Latin in the 12th century. However, it is not clear how these sources first came to be used during the
Renaissance, and their influence on what would later emerge as the discipline of psychology is a topic of scholarly debate.
Etymology and the early usage of the word The first print use of the term "psychology", that is, Greek-inspired neo-Latin
psychologia, is dated to multiple works dated 1525. Etymology has long been attributed to the
German scholastic philosopher Rudolf Göckel (1547–1628, often known under the Latin form
Rodolphus Goclenius), who published the
Psychologia hoc est: de hominis perfectione, animo et imprimis ortu hujus... in
Marburg in 1590. Croatian humanist
Marko Marulić (1450–1524) likely used the term in the title of a Latin treatise entitled
Psichiologia de ratione animae humanae (c.1510–1517). Although the treatise itself has not been preserved, its title appears in a list of Marulic's works compiled by his younger contemporary, Franjo Bozicevic-Natalis in his "Vita Marci Maruli Spalatensis" (Krstić, 1964). The term did not come into popular usage until the German Rationalist philosopher,
Christian Wolff (1679–1754) used it in his works
Psychologia empirica (1732) and
Psychologia rationalis (1734). This distinction between empirical and rational psychology was picked up in
Denis Diderot's (1713–1780) and
Jean le Rond d'Alembert's (1717–1783)
Encyclopédie (1751–1784) and was popularized in France by
Maine de Biran (1766–1824). In England, the term "psychology" overtook "mental philosophy" in the middle of the 19th century, especially in the work of
William Hamilton (1788–1856).
Enlightenment psychological thought Early psychology was regarded as the study of the soul (in the Christian sense of the term). The modern philosophical form of psychology was heavily influenced by the works of
René Descartes (1596–1650), and the debates that he generated, of which the most relevant were the objections to his
Meditations on First Philosophy (1641), published with the text. Also important to the later development of psychology were his
Passions of the Soul (1649) and
Treatise on Man (completed in 1632 but, along with the rest of
The World, withheld from publication after Descartes heard of the
Catholic Church's condemnation of
Galileo; it was eventually published posthumously, in 1664). Although not educated as a physician,
Descartes did extensive anatomical studies of bulls' hearts and was considered important enough that
William Harvey responded to him. Descartes was one of the first to endorse Harvey's model of the circulation of the blood, but disagreed with his metaphysical framework to explain it. Descartes dissected animals and human cadavers and as a result was familiar with the research on the flow of blood leading to the conclusion that the body is a complex device that is capable of moving without the soul, thus contradicting the "Doctrine of the Soul". The emergence of psychology as a medical discipline was given a major boost by
Thomas Willis, not only in his reference to psychology (the "Doctrine of the Soul") in terms of brain function, but through his detailed 1672 anatomical work, and his treatise ("Two Discourses on the Souls of Brutes"—meaning "beasts"). However, Willis acknowledged the influence of Descartes's rival, Pierre Gassendi, as an inspiration for his work. The philosophers of the British
Empiricist and
Associationist schools had a profound impact on the later course of experimental psychology.
John Locke's
An Essay Concerning Human Understanding (1689),
George Berkeley's
Treatise Concerning the Principles of Human Knowledge (1710), and
David Hume's
A Treatise of Human Nature (1739–1740) were particularly influential, as were
David Hartley's
Observations on Man (1749) and
John Stuart Mill's
A System of Logic. (1843). Also notable was the work of some Continental
Rationalist philosophers, especially
Baruch Spinoza's (1632–1677)
On the Improvement of the Understanding (1662) and
Gottfried Wilhelm Leibniz's (1646–1716)
New Essays on Human Understanding (completed 1705, published 1765). Another important contribution was
Friedrich August Rauch's (1806–1841) book
Psychology: Or, A View of the Human Soul; Including Anthropology (1840), the first English exposition of
Hegelian philosophy for an American audience.
German idealism pioneered the proposition of the
unconscious, which Jung considered to have been described psychologically for the first time by physician and philosopher
Carl Gustav Carus. Also notable was its use by
Friedrich Wilhelm Joseph von Schelling (1775–1835), and by
Eduard von Hartmann in
Philosophy of the Unconscious (1869); psychologist
Hans Eysenck writes in
Decline and Fall of the Freudian Empire (1985) that Hartmann's version of the unconscious is very similar to Freud's. The Danish philosopher
Søren Kierkegaard also influenced the humanistic, existential, and modern psychological schools with his works
The Concept of Anxiety (1844) and
The Sickness Unto Death (1849).
Transition to contemporary psychology Also influential on the emerging discipline of psychology were debates surrounding the efficacy of
Mesmerism (a precursor to hypnosis) and the value of
phrenology. The former was developed in the 1770s by Austrian physician
Franz Mesmer (1734–1815) who claimed to use the power of gravity, and later of "animal magnetism", to cure various physical and mental ills. As Mesmer and his treatment became increasingly fashionable in both Vienna and Paris, it also began to come under the scrutiny of suspicious officials. In 1784, an investigation was commissioned in Paris by King
Louis XVI which included American ambassador
Benjamin Franklin, chemist
Antoine Lavoisier and physician
Joseph-Ignace Guillotin (later the popularizer of the guillotine). They concluded that Mesmer's method was useless.
Abbé Faria, an Indo-Portuguese priest, revived public attention in animal magnetism. Unlike Mesmer, Faria claimed that the effect was 'generated from within the mind' by the power of expectancy and cooperation of the patient. Although disputed, the "magnetic" tradition continued among Mesmer's students and others, resurfacing in England in the 19th century in the work of the physician
John Elliotson (1791–1868), and the surgeons
James Esdaile (1808–1859), and
James Braid (1795–1860) (who reconceptualized it as property of the subject's mind rather than a "power" of the Mesmerist's, and relabeled it "hypnotism"). Mesmerism also continued to have a strong social (if not medical) following in England through the 19th century (see Winter, 1998). Faria's approach was significantly extended by the clinical and theoretical work of
Ambroise-Auguste Liébeault and
Hippolyte Bernheim of the
Nancy School. Faria's theoretical position, and the subsequent experiences of those in the Nancy School made significant contributions to the later autosuggestion techniques of
Émile Coué. It was adopted for the treatment of
hysteria by the director of Paris's
Salpêtrière Hospital,
Jean-Martin Charcot (1825–1893).
Phrenology began as "organology", a theory of brain structure developed by the German physician,
Franz Joseph Gall (1758–1828). Gall argued that the brain is divided into a large number of functional "organs", each responsible for particular human mental abilities and dispositions – hope, love, spirituality, greed, language, the abilities to detect the size, form, and color of objects, etc. He argued that the larger each of these organs are, the greater the power of the corresponding mental trait. Further, he argued that one could detect the sizes of the organs in a given individual by feeling the surface of that person's skull. Gall's ultra-localizationist position with respect to the brain was soon attacked, most notably by French anatomist
Pierre Flourens (1794–1867), who conducted ablation studies (on chickens) which purported to demonstrate little or no cerebral localization of function. Although Gall had been a serious (if misguided) researcher, his theory was taken by his assistant,
Johann Gaspar Spurzheim (1776–1832), and developed into the profitable, popular enterprise of phrenology, which soon spawned, especially in Britain, a thriving industry of independent practitioners. In the hands of Scottish religious leader
George Combe (1788–1858) (whose book
The Constitution of Man was one of the best-sellers of the century), phrenology became strongly associated with political reform movements and egalitarian principles (see, e.g., Shapin, 1975; but also see van Wyhe, 2004). Spurzheim soon spread phrenology to America as well, where itinerant practical phrenologists assessed the mental well-being of willing customers (see Sokal, 2001; Thompson 2021). The development of modern psychology was closely linked to
psychiatry in the eighteenth and nineteenth centuries (see
History of psychiatry), when the treatment of the mentally ill in hospices was revolutionized after Europeans first considered their pathological conditions. In fact, there was no distinction between the two areas in psychotherapeutic practice, in an era when there was still no drug treatment (of the so-called
psychopharmacologicy revolution from 1950) for mental disorders, and its early theorists and pioneering clinical psychologists generally had medical background. The first to implement in the Western a humanitarian and scientific treatment of
mental health, based on
Enlightenment ideas, were the French
alienists, who developed the empirical observation of
psychopathology, describing the clinical conditions, their physiological relationships and classifying them. It was called the rationalist-empirical school, which most known exponents were
Pinel,
Esquirol,
Falret,
Morel and
Magnan. In the late nineteenth century, the French current was gradually overcome by the German field of study. At first, the German school was influenced by
romantic ideals and gave rise to a line of mental process speculators, based more on
empathy than reason. They became known as
Psychiker, mentalists or psychologists, with different currents being highlighted by
Reil (creator of the word "psychiatry"),
Heinroth (first to use the term "
psychosomatic")
Ideler and
Carus. In the middle of the century, a "somatic reaction" () formed against the speculative doctrines of mentalism, and it was based on
neuroanatomy and
neuropathology. In it, those who made important contributions to the psychopathological classification were
Griesinger,
Westphal,
Krafft-Ebbing and
Kahlbaum, which, in their turn, would influence
Wernicke and
Meynert.
Kraepelin revolutionized as the first to define the diagnostic aspects of mental disorders in
syndromes, and the work of psychological classification was followed to the contemporary field by contributions from
Schneider,
Kretschmer,
Leonhard, and
Jaspers. In
Great Britain, there stand out in the nineteenth century
Alexander Bain founder of the first journal of psychology,
Mind, and writer of reference books on the subject at the time, such as
Mental Science: The Compendium of Psychology, and the History of Philosophy (1868), and
Henry Maudsley. In
Switzerland,
Bleuler coined the terms "
depth psychology", "
schizophrenia", "
schizoid" and "
autism". In the
United States, the Swiss psychiatrist
Adolf Meyer maintained that the patient should be regarded as an integrated "
psychobiological" whole and emphasized
psychosocial factors, lending support to early conceptions of "
psychosomatic medicine", a precursor to
behavioral medicine and other fields. ==Emergence of German experimental psychology==