Upon this distinction of the instinct into its two-fold character, hinges the chief point in the present discussion. It sometimes happens, nay, it happens every day and hour, that mankind obey its impulses, not from any calculation of consequences, but simply from animal impulse. Thus many children that are brought into the world owe their existence, not to deliberate conviction in their parents that their birth was really desirable, but simply to an unreasoning instinct, which men, in the mass, have not learnt either to resist or control. It is a serious question—and surely an exceedingly proper and important one—whether man can obtain, and whether he is benefitted by obtaining, control over this instinct. IS IT DESIRABLE, THAT IT SHOULD NEVER BE GRATIFIED WITHOUT AN INCREASE TO POPULATION? OR, IS IT DESIRABLE, THAT IN GRATIFYING IT, MAN SHALL BE ABLE TO SAY WHETHER OFFSPRING SHALL BE THE RESULT OR NOT? To answer the questions satisfactorily, it would be necessary to substantiate, that such control may be obtained without the slightest injury to the physical health, or violence to the moral feelings; and also, that it should be obtained without any real sacrifice of enjoyment; or, if that cannot be, with as little as possible. Thus have I plainly stated the subject. It resolves itself, as my readers may observe, into two distinct heads; first, the _desirability_ of such control; and, secondly, its _possibility_. In discussing its desirability, I enter a wide field—a field often traversed by political economists, by moralists, and by philosophers, though generally, it will be confessed, to little purpose. This may be, in a great measure, attributed rather to their fear than their ignorance. The world would not permit them to say what they knew. I intend that my readers shall know all that I know on the subject; for I have long since ceased to ask the world’s leave to say what I think, and what I believe to be useful to the public. I propose to begin by considering the question in the abstract, and then to examine it in its political and social bearings. CHAPTER III. THE QUESTION EXAMINED IN THE ABSTRACT. Is it in itself desirable, that man should obtain control over the instinct of reproduction, so as to determine when its gratification shall produce offspring, and when it shall not?