PREFACE xvii 



Full of enthusiasm, too, is the song that Lluria 

 sings of the indefinite perfectibility of the brain, of 

 this vital organ, eternally young, that we all have 

 within us. The former slave of cosmic forces 

 which sculptured, with painful minuteness, the 

 network of its associated passages, the human 

 brain is destined one day to become the tyrant of 

 that same natural energy to which it owes its 

 appearance. Certain it is that the senses, the too 

 narrow windows of the soul, have broken the 

 continuity of the scale of ethereal vibrations, 

 obliging us to select only the most useful for the 

 increase and prosperity of the species ; but equally 

 so is it that, by a wise compensation, our cere- 

 bral cortex, exquisitely plastic and creative, has 

 succeeded in filling with ideas and inventions the 

 gaps in the diminishing sensory register. What 

 are the instruments of science, the microscope and 

 the telescope, the galvanometer, and the photo- 

 graphic camera, the screen of the radioscope, and 

 the resources of analytic chemistry, but retinas and 

 complementary apparatus, perceived from afar, in 

 virtue of which human ingenuity, correcting Nature, 

 enters into possession of all the palpitations of 

 cosmic energy ? 



I have done ; for it is not my intention to sully 

 with inapposite commentary the diverse and 

 seductive themes which, with abundance of erudi- 



