In 1881, the Polish-German neuropsychiatrist Emanuel Mendel published one of the most influential monographs on mania in the last half of 19th century, always prominently cited by Kraepelin in his multiple textbook editions. The monograph has neither been translated into English nor extensively discussed in the modern Anglophonic literature. Over 10 chapters and 196 pages, Mendel presents a detailed historical, clinical, and etiologic review of the manic syndrome that includes, for the first time, the syndrome of hypomania. He argued against the concepts of mania as a non-specific agitated psychotic state or a stage in a unitary model of psychosis. His vivid descriptions of the key signs and symptoms included all modern diagnostic criteria. Mania had, he asserted, the best prognosis of any major psychiatric disorder but observed, especially in periodic mania after multiple episodes, full restitutio ad integrum was not always achieved. On recovery, he noted that many manic patients described their experiences as states of intoxication or being “in a dream.” This essay accompanied, by an on-line complete English translation of Mendel's monograph, along with 12 of his 26 case histories, provides the opportunity for Anglophonic clinicians, students, and scholars to access this historically important essay on Mania. His clinical view of mania is very similar to our modern conceptions although he considers the psychomotor/cognitive and not the mood changes to be primary. Although Mendel noticed the close temporal connection between melancholic and manic syndromes, he nonetheless considered them to be distinct syndromes.