For all these reasons, death control is achieved very easily, birth control is achieved with great difficulty. Death rates have therefore fallen in recent years with startling suddenness. But birth rates have either remained at their old high level or, if they have fallen, have fallen very little and at a very slow rate. In consequence, human numbers are now increasing more rapidly than at any time in the history of the species.

Moreover, the yearly increases are themselves in­creasing. They increase regularly, according to the rules of compound interest; and they also increase irregularly with every application, by a technologically backward society of the principles of Public Health. At the present time the annual increase in world pop­ulation runs to about forty-three millions. This means that every four years mankind adds to its numbers the equivalent of the present population of the United States, every eight and a half years the equivalent of the present population of India. At the rate of increase prevailing between the birth of Christ and the death of Queen Elizabeth I, it took sixteen centuries for the population of the earth to double. At the present rate it will double in less than half a century. And this fantastically rapid doubling of our numbers will be taking place on a planet whose most desirable and pro­ductive areas are already densely populated, whose soils are being eroded by the frantic efforts of bad farmers to raise more food, and whose easily available mineral capital is being squandered with the reckless extravagance of a drunken sailor getting rid of his accumulated pay.

In the Brave New World of my fable, the problem of human numbers in their relation to natural resources had been effectively solved. An optimum figure for world population had been calculated and numbers were maintained at this figure (a little under two bil­lions, if I remember rightly) generation after genera­tion.