In considering the data furnished by these intelligence tests we should remember several factors that should be taken into consideration.  Irrespective of other considerations, children who are underfed, undernourished, crowded into badly ventilated and unsanitary homes and chronically hungry cannot be expected to attain the mental development of children upon whom every advantage of intelligent and scientific care is bestowed.  Furthermore, public school methods of dealing with children, the course of studies prescribed, may quite completely fail to awaken and develop the intelligence.

The statistics indicate at any rate a surprisingly low rate of intelligence among the classes in which large families and uncontrolled procreation predominate.  Those of the lowest grade in intelligence are born of unskilled laborers (with the highest birth rate in the community); the next high among the skilled laborers, and so on to the families of professional people, among whom it is now admitted that the birth rate is voluntarily controlled.(3)

But scientific investigations of this type cannot be complete until statistics are accurately obtained concerning the relation of unrestrained fecundity and the quality, mental and physical, of the children produced.  The philosophy of Birth Control therefore seeks and asks the cooperation of science and scientists, not to strengthen its own “case,” but because this sexual factor in the determination of human history has so long been ignored by historians and scientists.  If science in recent years has contributed enormously to strengthen the conviction of all intelligent people of the necessity and wisdom of Birth Control, this philosophy in its turn opens to science in its various fields a suggestive avenue of approach to many of those problems of humanity and society which at present seem to enigmatical and insoluble.

     (1) Conklin, The Direction of Human Evolution, pp. 125,
     126.

(2) The Glands Regulating Personality:  A study of the glands of internal secretion in relation to the types of human nature.  By Louis Berman, M. D., Associate in Biological Chemistry, Columbia University; Physician to the Special Health Clinic.  Lenox Hill Hospital.  New York:  1921.

(3) Cf Terman:  Intelligence of School Children.  New York 1919. p. 56.  Also, “Is America Safe for Democracy?” Six lectures given at the Lowell Institute of Boston, by William McDougall, Professor of Psychology in Harvard College.  New York, 1921.

CHAPTER XI:  Education and Expression