After a somewhat careful study of written history, and after an investigation extending over several years of all the accessible facts relative to extant tribes representing the various stages of human development, I had reached the conclusion, as early as the year 1882, that the female organism is in no wise inferior to that of the male. For some time, however, I was unable to find any detailed proof that could consistently be employed to substantiate the correctness of this hypothesis.  
In the year 1885, with no special object in view other than a desire for information, I began a systematized investigation of the facts which at that time had been established by naturalists relative to the development of mankind from lower orders of life. It was not, however, until the year 1886, after a careful reading of The Descent of Man, by Mr. Darwin, that I first became impressed with the belief that the theory of evolution, as enunciated by scientists, furnishes much evidence going to show that the female among all the orders of life, man included, represents a higher stage of development than the male.vi Although at the time indicated, the belief that man has descended from lower orders in the scale of being had been accepted by the leading minds both in Europe and America, for reasons which have not been explained, scientists, generally, seemed inclined to ignore certain facts connected with this theory which tend to prove the superiority of the female organism.
 
Scarcely considering at the outset whether my task would eventually take the form of a magazine article, or whether it would be extended to the dimensions of a book, I set myself to work to show that some of the conclusions of the savants regarding the subject of sex-development are not in accord with their premises.
 
While writing the first part of this volume, and while reasoning on the facts established by scientists in connection with the observations which have been made in these later years relative to the growth of human society and the development of human institutions, it seemed clear to me that the history of life on the earth presents an unbroken chain of evidence going to prove the importance of the female; and, so struck was I by the manner in which the facts of science and those of history harmonize, that I decided to embrace within my work some of the results of my former research. I therefore set about the task of tracing, in a brief manner, the growth of the primary characters observed in the two diverging sex-columns, according to the factsvii and principles enunciated in the theory of natural development.
 
It is not perhaps singular, during an age dominated by theological dogmatism, and in which no definite knowledge relative to the development of life on the earth had been gained, that man should have regarded himself as an infinitely superior being. Neither is it remarkable that woman, who was supposed to have appeared later on the scene of action than did her male mate, and who owed her existence to a surgical operation performed upon him, should have been regarded simply as an appendage, a creature brought forth in response to the requirements of the masculine nature.
 
The above doctrines when enunciated by theologians need cause little surprise, but with the dawn of a scientific age it might have been expected that the prejudices resulting from those doctrines might disappear. When, however, we turn to the most advanced scientific writings of the present century, we find that the prejudices which throughout thousands of years have been gathering strength are by no means eradicated, and any discussion of the sex question is still rare in which the effects of these prejudices may not be traced. Even Mr. Darwin, notwithstanding his great breadth of mental vision and the important work which he accomplished in the direction of original inquiry, whenever he had occasion to touch on the mental capacities of women, or more particularlyviii on the relative capacities of the sexes, manifested the same spirit which characterizes the efforts of an earlier age; and throughout his entire investigation of the human species, his ability to ignore certain facts which he himself adduced, and which all along the line of development tend to prove the superiority of the female, is truly remarkable.
 
We usually judge of a man’s fitness to assume the r?le of an original investigator in any branch of human knowledge, by noting his powers of observation and generalization, and by observing his capacity to perceive connections between closely related facts; also, by tracing the various processes by which he arrives at his conclusions. The ability, however, to collect facts, and the power to generalize and draw conclusions from them, avail little, when brought into direct opposition to deeply rooted prejudices.
 
The indications are strong that the time has at length arrived when the current opinions concerning sex capacity and endowment demand a revision, and when nothing short of scientific deductions, untainted by the prejudices and dogmatic assumptions of the past, will be accepted.
 
As has been stated, the object of this volume is to set forth the principal data brought forward by naturalists bearing on the subject of the origin and development of the two lines of sexual demarcation, and by means of the facts observed by explorers among peoples in the various stages ofix development, to trace, so far as possible, the effect of such differentiation upon the individual, and upon the subsequent growth of human society.
 
E. B. G.