This work is designed as a supplement to the author's work on Neurasthenia (Nervous Exhaustion). In the preface to Nervous Exhaustion it was stated that the chapter on the causes was designedly omitted, inasmuch as a thorough elucidation of that side of the subject, in all its relations and dependencies, would be of so complex a character as to require a special volume of itself. The present work is, therefore, to be regarded as a chapter on causes for the treatise on Nervous Exhaustion, with these qualifications--that it embraces the whole domain of nerve sensitiveness and nerve susceptibility, that lead to the more definite condition of nervous exhaustion, and that it is of a more distinctly philosophical and popular character than that treatise, which was specially addressed to the professional and scientific reader. To those who are beginning the study of this interesting theme the following epitome of the philosophy of this work may be of assistance, as a preliminary to a detailed examination. (1) Nervousness is strictly deficiency or lack of nerve-force. This condition, together with all the symptoms of diseases that are evolved from it, has developed mainly within the nineteenth century, and is especially frequent and severe in the Northern and Eastern portions of the United States. (2) The chief and primary cause of this development and very rapid increase of nervousness is modern civilization, which is distinguished from the ancient by these five characteristics : steampower, the periodical press, the telegraph, the sciences, and the mental activity of women. (3) Secondary and tertiary causes (i.e., climate, institutions--civil, political, and religious, social and business--personal habits, indulgence of appetites and passions) are of themselves without power to induce nervousness, save when they supplement and are interwoven with the modern forms of civilization. (4) The sign and type of functional nervous diseases that are evolved out of this general nerve sensitiveness is neurasthenia (nervous exhaustion). (5) The greater prevalence of nervousness in America is a complex resultant of a number of influences, the chief of which are dryness of the air, extremes of heat and cold, civil and religious liberty, and the great mental activity made necessary and possible in a new and productive country under such climatic conditions. (PsycINFO Database Record (c) 2004 APA, all rights reserved).