It seems to be a generally prevalent opinion that the marriage ceremony removes all restraint from the exercise of the sexual functions. Few seem to even suspect that the seventh commandment has any bearing upon sexual conduct within the pale of matrimony. Yet if we may believe the confessions and statements of men and women, legalized prostitution is a more common crime than illicit commerce of the sexes. So common is the popular error upon this subject, and so strongly fortified by prejudice is it, that it is absolutely dangerous for a writer or speaker to express the truth, if he knows it and has a disposition to do so. Any attempt to call attention to true principles is mocked at, decried, stigmatized, and, if possible, extinguished. The author is vilified, and his work is denounced, and relegated to the ragman. Extremist, fanatic, ascetic, are the mildest terms employed concerning him, and he escapes with rare good fortune if his chastity or virility is not assailed. We are not going to run any such risks, and so shall not attempt to enunciate or maintain any theory. We shall content ourselves with plainly stating established physiological facts by quotations from standard medical authors, leaving each reader to draw conclusions and construct a practical formula for himself. Object of the Reproductive Functions.--Man, in whatever condition we find him, is more or less depraved. This is true as well of the most cultivated and refined ladies and gentlemen of the great centers of civilization, as of the misshapen denizens of African jungles, or the scarcely human natives of Australia and Terra del Fuego. His appetites, his tastes, his habits, even his bodily functions are perverted. Of course, there are degrees of depravity, and varieties of perversion. In some respects, savages approach more nearly to the natural state than civilized man, and in other particulars, the latter more nearly represents man's natural condition; but in neither barbarism nor civilization do we find man in his primitive state. In consequence of this universal departure from his original normal condition,--the causes of which we need not here trace, since they are immaterial in the consideration of this question,--when we wish to ascertain with certainty the functions of certain organs of the human body, we are obliged to compare them with the corresponding organs of lower animals, and study the functions of the latter. It is by this method of investigation that most of the important truths of physiology have been developed; and the plan is universally acknowledged to be a proper and logical one.