The demand for a second edition of this book in little more than a week after the publication of the first, indicates the interest which the public take in the relation of Sex to Education, and justifies the author in appealing to physiology and pathology for light upon the vexed question of the appropriate education of girls. Excepting a few verbal alterations, and the correction of a few typographical errors, there is no difference between this edition and the first. The author would have been glad to add to this edition a section upon the relation of sex to women's work in life, after their technical education is completed, but has not had time to do so. BOSTON, 18 ARLINGTON STREET, Nov. 8, 1873. NOTE TO THE FIFTH EDITION. The attention of the reader is called to the definition of "education" on the twentieth page. It is there stated, that, throughout this essay, education is not used in the limited sense of mental or intellectual training alone, but as comprehending the whole manner of life, physical and psychical, during the educational period; that is, following Worcester's comprehensive definition, as comprehending instruction, discipline, manners, and habits. This, of course, includes home-life and social life, as well as school-life; balls and parties, as well as books and recitations; walking and riding, as much as studying and sewing. When a remission or intermission is necessary, the parent must decide what part of education shall be remitted or omitted,--the walk, the ball, the school, the party, or all of these. None can doubt which will interfere most with Nature's laws,--four hours' dancing, or four hours' studying. These remarks may be unnecessary. They are made because some who have noticed this essay have spoken of it as if it treated only of the school, and seem to have forgotten the just and comprehensive signification in which education is used throughout this memoir. Moreover, it may be well to remind the reader, even at the risk of casting a reflection upon his intelligence, that, in these pages, the relation of sex to mature life is not discussed, except in a few passages, in which the large capacities and great power of woman are alluded to, provided the epoch of development is physiologically guided. SEX IN EDUCATION. PART I. INTRODUCTORY. "Is there any thing better in a State than that both women and men be rendered the very best? There is not."--PLATO.