Wilhelm Griesinger was born in Stuttgart in 1817. In 1842, with two friends, he founded the Archiv für physiologische Heilkund, which became one of the most important instruments in the reform of German medicine in the mid-nineteenth century. After studying at Tübingen and Zürich, Grieesinger worked for two years with Ernst Albert von Zeller at Winnenthal. On the basis of his experience there, he published the first edition of his Pathologie und Therapie der Psychischen Krankheiten in 1845, a textbook that secured his reputation as one of the leading figures in modern 'scientific psychiatry.' It was expanded in 1861 and translated into English, as Mental Pathology and Therapeutics, in 1867.

Griesinger began his Mental Pathology and Therapeutics with a plea for the localization of mental diseases and their symptoms. There was no doubt in his mind that brain is the seat of mental diseases. He is know for writing: "Psychological diseases are diseases of the brain," and "Insanity is merely a symtom complex of various anomalous states of the brain."

Drawing on neurophysicological work defining the spinal reflex arc, Griesinger postulated a 'mental reflex' (psychische Reflexaktion) in the brain. Just as physical sensations stimulated spinal reflexes, he argued, representations (Vorstellungen) maintained the 'psychological tonus' or character of the individual. Psychological disorders arose when the mechanisms governing the 'mental reflexes' broke down. When the mental reflex was retarded, melancholia resulted. When it was excessively active, the result was mania.

While Griesinger believed that mental disorders had a physical origin, he differed from members of the Somatiker school such as Maxmilian Jacobi, Friedrich Nasse and Christian Friedrich Flemming, who saw madness not primarily as a disease of the brain, but rather as the consequence of diseases in oother parts of the body.

Griesinger argued not only that madness was a disease of the brain, but that it was the consequence of a single disease of the brain. According to this concept of the 'unitary psychosis' (Einheitspsychose) the manifold symptoms of madness were not the result of different diseases but different stages of a single disease process. Griesinger adapted  his idea of the 'unitary psychosis'  from that of  his mentor Zeller. Where Zeller believed that it was the unified human soul or character (Gemüt) that was afflicted in madness, Griesinger believed that character was nothing more than the psychological tonus produced through the accumulation of representations over the lifetime of  a person. For Griesinger the soul became a function of the brain.

Over the next twenty years he worked in internal medicine, publishing a famous book on infectious diseases in 1857. In 1865 he moved to Berlin to accupy the chair in Psychiatry and Neurology.

In 1868 he published 'On Asylums and their Further Development in Germany," a controversial and ultimately very influential proposal for the reform of the institutional care of the mentally ill.

He died in 1869.

References
Erwin Acherknecht, A Short History of Psychiatry, [Hafner, 1968] p.64
Eric J. Engstrom, Clinical Psychiatry in Imperial Germany. [Cornell U. P., 2003] pp. 58-9.

    The cases  "An officer," "Masturbation and Madness," and "Lovesickness" are taken from  the 1867 English translation of Griesinger's text. By the time of the English translation Griesinger's views on the nature of insanity were "well nigh universaly admitted to be correct." During the late nineteenth century it was the most widely used text in psychiatry. This popularity was no doubt due to the combination of Griesinger's astute clinical observations and his strict adherance to the principle that mental diseases were not inherently different from other diseases of the nervous system.

See: Wilhelm Griesinger:Mental Pathology and Therapeutics (New York,William Wood & Co., 1882)
See: Otto Marx, :Wilhelm Griesinger and the History of Psychiatry: A Reassessment", Bulletin of the History of Medicine, 46:519-544 (1972)