If man, then, can obtain control over this most important of instincts, it is, _in principle_, right that he should know it. If men, after obtaining such knowledge, think fit not to use it; if they deem it nobler and more virtuous, to follow each animal impulse, like the beasts of the field and the fowls of the air, without a thought of its consequences, or an enquiry into its nature—then let them do so. The knowledge that they have the power to act more like rational beings, will not injure, if it fail to benefit them. They are at perfect liberty to set it aside, to neglect it, to forget it, if they can. Only let them show common sense enough to permit that others, who are more slow to incur sacred responsibilities, and more willing to give reason the control of instinct, should obtain the requisite knowledge, and follow out their prudent resolutions. If this little book were in the hands of every adult in the United States, not one need profit by it, unless he sees fit. Nor will any man admit that he can possibly be injured by it. Oh no. _His_ virtue can bear any quantity of light. But then, his neighbour’s, or his son’s, or his daughter’s! This would lead me to discuss the _social bearings_ of the question. But, as conceiving it more in order, I shall first speak of it in connexion with political economy. CHAPTER IV. THE QUESTION IN ITS CONNEXION WITH POLITICAL ECONOMY. The population question, as it is called, has of late years occupied much attention, especially in Great Britain. It was first prominently brought forward and discussed, through two large volumes, by Malthus, an English clergyman. Godwin, Ricardo, Thompson, Place, Mill, and other celebrated cotemporary writers, have all discussed it, with more or less reserve, and at greater or less length.