168 THE CONTROL OF LIFE 



densed recapitulation of the racial evolution. This is 

 an important and luminous idea, but it requires to be 

 used very carefully. 



In the first chapter in man's life- cycle, there is cer- 

 tainly much that may be described as recapitulation 

 of racial evolution, such as the almost evanescent de- 

 velopment of the old-fashioned dorsal axis, the noto- 

 chord, which is speedily replaced by its substitute the 

 backbone. But it is obvious that the child we know 

 does not work through the history of human acquisi- 

 tions, e.g. in learning to speak. That is happily un- 

 necessary, for while many strides in the evolution of 

 aptitudes are enregistered internally in the hereditary 

 constitution, many others are enregistered externally 

 in man's permanent products. Part of the business of 

 education is to shorten the recapitulation such as it is 

 by supplying children with a thought-out succession 

 of appropriate liberating stimuli which enable the inborn 

 hereditary organisation to make in a few years advances 

 which meant for the race the patience of ages. A Hber- 

 ating stimulus means in the domain of things a spark 

 to a barrel of gunpowder, which leads to self-destruction, 

 the releasing of a spring which sets the gramophone 

 unwinding. Among living creatures it means the en- 

 trance of the sperm-cell that sets the egg-cell developing, 

 the rise of temperature and the insoaking of moisture 

 that prompt a seed to germinate, the touch of a twig 

 that sets a tendril twining, the diffusion of an internal 

 secretion that calls a dormant structure into activity. 

 For children a liberating stimulus means all sorts of 



