“The author, Doctor Knowlton, professes to deal with the subject of population.  Now, a century ago a great and important question of political economy was brought to the attention of the scientific and thinking world by a man whose name everybody is acquainted with, namely, Malthus.  He started for the first time a theory which astonished the world, though it is now accepted as an irrefragable truth, and has since been adopted by economist after economist.  It is that population has a strong and marked tendency to increase faster than the means of subsistence afforded by the earth, or that the skill and industry of man can produce for the support of life.  The consequence is that the population of a country necessarily includes a vast number of persons upon whom poverty presses with a heavy and sad hand.  It is true that the effects of over-population are checked to a certain extent by those powerful agencies which have been at work since the beginning of the world.  Great pestilences, famines, and wars have constantly swept away thousands from the face of the earth, who otherwise must have contributed to swell the numbers of mankind.  The effect, however, of this tendency to increase faster than the means of subsistence, leads to still more serious evils amongst the poorer classes of society.  It necessarily lowers the price of labor by reason of the supply exceeding the demand.  It increases the dearth of provisions by making the demand greater than the supply, and produces direful consequences to a large class of persons who labor under the evils, physical and moral, of poverty.  You find it, as described by a witness called yesterday, in the overcrowding of our cities and country villages, and the necessarily demoralising effects resulting from that over-crowding.  You have heard of the way in which women—­I mean child-bearing women—­are destroyed by being obliged to submit to the necessities of their position before they are fully restored from the effects of child-birth, and the effects thus produced upon the children by disease and early death.  That these are evils—­evils which, if they could be prevented, it would be the first business of human charity to prevent—­there cannot be any doubt.  That the evils of over-population are real, and not imaginary, no one acquainted with the state of society in the present day can possibly deny.  Malthus suggested, years ago, and his suggestion has been supported by economists since his time, that the only possible way of keeping down population was by retarding marriage to as late a period as possible, the argument being that the fewer the marriages the fewer would be the people.  But another class of theorists say that that remedy is bad, and possibly worse than the disease, because, although you might delay marriage, you cannot restrain those instincts which are implanted in human nature, and people will have the gratification and satisfaction of passions powerfully implanted, if not in one way, in some other