On the occasion of the inauguration of the new and magnificent buildings of the Medical School of Harvard University in Boston, President Eliot and Dr. J.J. Putnam, professor of the diseases of the nervous system, asked me to deliver before the students some lectures about pathological psychology. I greatly appreciated this honour, and tried to sum up before the American students some elementary psychological researches about a well-known disease, Hysteria, in order to show them how the study of the mental state of the patient can sometimes be useful to explain many disturbances and to give some unity to apparently discordant symptoms. So the following fifteen lectures were given in the Harvard Medical School between the fifteenth of October and the end of November, 1906. The kind reception these lectures on hysteria have met with encourages us to publish a second edition of this work. It does not seem to us very useful to modify it profoundly, for the interest of a scientific work resides almost always in the date at which it was drawn up, and one should not confusedly mix the ideas of one period with those of another. I only wish to show in a short preface that certain notions set forth in these lectures of 1906 have spread very much since that date and have played a great part in the interpretation of hysteria. (PsycINFO Database Record (c) 2006 APA, all rights reserved).