All things having life, increase and multiply upon an analogous principle, but the method of effecting that increase differs very considerably. In the human race, nature has furnished the sexes parts, which it is necessary for the purpose of reproduction, should approximate and commingle their elements or rudiments of future existence, and that, that intermixture should take place in the womb of the female. In some of the lower order of animals and in the vegetable world the sexes are combined in one object which object possesses the power of increase. To enter into the physiological minutæ of impregnation would be embarking more scientifically in these matters than this little book professes to do, it being our intention more to hold up a popular view than to discuss the various opinions upon any given point. It is exceedingly to be regretted that mankind did not spend some small portion, at least, of the time and industry which has been wasted on theoretical researches, in collecting and collating the _actual experience_ of human beings. But this task, too difficult for the ignorant, has generally been thought too simple and common-place for the learned. To this circumstance, joined to the fact, that it is not thought fitting or decent for human beings freely to communicate their personal experience on the important subject now under consideration—to these causes are attributable the great and otherwise unaccountable ignorance which so strangely prevails, even sometimes among medical men, as to the power which man may possess over the reproductive instinct. Many physicians will positively deny that man possesses any such power. And yet, if the thousandth part of the talent and research had been employed to investigate this momentous fact, which has been turned to the building up of idle theories, no commonly intelligent individual could well be ignorant of the truth. I have taken great pains to ascertain the opinions of the most enlightened physicians of Great Britain and France on this subject; (opinions which popular prejudice will not permit them to offer publicly in their works;) and they all concur in admitting, what the experience of the French nation _positively proves_, that man may have a perfect control over this instinct: and that men and women may, without any injury to health, or the slightest violence done to the moral feelings, and with but small diminution of the pleasure which accompanies the gratification of the instinct, refrain at will from becoming parents. It has chanced to me, also, to win the confidence of several individuals, who have communicated to me, without reserve, their own experience: and all this has been corroborative of the same opinion.