They satisfy their desires as they arise, whether it be the desire for food or the desire of sex.
The very poor includes amongst its numbers, the drunkard, the criminal, the professional pauper, and the physically and mentally defective.
The drunkard is not distinguished by his prudence, nor by his self-restraint.

In fact the alcohol which he imbibes paralyses what self-control he has, and excites through an increased circulation in his lower brain-centres an unnatural sexual desire.

What hope is there of the drunkard curtailing his family by self-restraint?
Dr.Billings says, (Forum, June 1893) "So far as we have data with regard to the use of intoxicating liquors, fertility seems greatest in those countries and amongst those classes where they are most freely used." Neither is the criminal blessed with the important attributes of prudence and self-control.

They are conspicuous by their absence in him.
In all defectives, in epileptics, idiots, the physical deformed, the insane, and the criminal, the prudence and self-restraint necessary to the limitation of families is either partially or entirely absent.
To the poor in crowded localities, with limited room-space and insanitary surroundings, effective self-restraint is more difficult than in any other class of society.
In all defectives the sexual instinct is as strong, if not stronger, than in the normal, and they have not that interest in life, and regard for the future that suggest restraint, nor have they the power to practise it though prudence were to guide them.
The higher checks to population, as they exist among the better classes of people, do not obtain amongst the defectives taken as a class.
Vice and misery are more active checks amongst the very poor, and abortion is practised to a very considerable extent, but the appalling fact remains, that the birth-rate of the unfit goes on undisturbed, while the introduction of higher checks amongst the normal classes has led to a marked decline, more marked than at first sight appears.

The worst feature of the problem, however, is not so much the disproportion in the numbers born to the normal and the abnormal respectively, but the fact that the defectives propagate their kind.
The defectives, whose existence and whose liberty constitute the greatest danger to the State, are the intermittent inhabitants of our lunatic asylums, prisons, and reformatories.
There is one defect common to all these, and that is defective inhibition.
All human activity is the result of two forces, motor impulses tending to action, and inhibition tending to inertia.
The lower animals have strong motor impulses constantly exploding and expressing themselves in great activity, offensive, defensive, self-preservative, and procreative, being restrained only by the inhibitive forces of their conditions and environment.
Children have strong motor impulses, which are at first little controlled.