executive or artistic ability. Mental abilities are much subdivided and are inherited separately. Mr. Redfield's idea of the process is much too
Moreover, Mr. Redfield's whole conception of the increase of intelligence with increase of age in a parent shows a disregard of the facts of psychology. As E. A. Doll has pointed out,79 in criticising Mr. Redfield's recent and extreme claim that feeble-mindedness is the product of early marriage, it is incorrect to speak of 20-, 30-, or 40-year standards of intelligence; for recent researches in measurement of mental development indicate that the heritable standard of intelligence of adults increases very little beyond the age of approximately 16 years. A person 40 years old has an additional experience of a quarter of a century, and so has a larger mental content, but his intelligence is still nearly at the 16-year level. Mental activity is the effect, not the cause, of mental growth or development. Education merely turns inherent mental powers to good account; it makes very little change in those powers themselves. To suppose that a father can, by study, raise his innate level of intelligence and transmit it at the new level to his son, is a naïve idea which finds no warrant in the known facts of mental development.
- In his entire conception of the storing-up and transmission of energy, Mr. Redfield has fallen victim to a confusion of ideas due to the use of the same word to mean two different things. He thinks of energy as an engineer; he declares the body-cell is a storage battery; he believes that the athlete by performing work stores up energy in his body (in some mysterious and unascertainable way) just as the clock stores up energy when it is wound. The incorrectness of supposing that the so-called energy of a