INTRODUCTION xi 



his knowledge, not only by wide reading, but by constant 

 original investigation. To support this exact knowledge, 

 Huxley employed his great power of lucid and accurate, 

 though popular, oral expression. The result is seen in 

 readable scientific essays like that On a Piece of Chalk, 

 found in this volume. 



Unfortunately about this time Huxley began to suffer 

 from poor health, dating back, perhaps, to the attack of 

 poisoning he mentions in the Autobiography. For these 

 attacks walking-tours proved" the best medicine, and they 

 took him a-field in England and Switzerland. His com- 

 panion often was his friend Tyndall, the noted physicist. 



In 1859 ^^'^s published that epoch-making book by one 

 of Huxley's friends, Charles Darwin, entitled The Origin 

 of Species by Means of Natural Selection. The publica- 

 tion of this volume became for Huxley a momentous event. 

 For it soon developed that he was to be the great champion 

 of 'what came to be called "Darwinism." The scientific 

 views his friend had expressed were so novel and antago- 

 nistic to what people had long believed that they were 

 attacked vigorously by many scientists and clergymen. 

 Huxley, animated by an abiding and fearless love of truth, 

 came to the defence of his friend. Using his great powers 

 of thought and expression, Huxley explained and championed 

 Darwin's views before various kinds of audiences. He 

 wrote essays to promulgate this new doctrine. He debated 

 the question with Bishop Wilberforce. He lectured upon 

 it before the Royal Institution, at the University of Edin- 

 burgh, and to workingmen. Of one of these lectures a 

 competent critic said: " I never remember an address 

 listened to with such applause." So clear and forceful 

 was his popular presentation of Darwinism in the lectures 

 to workingmen that the thin little volumes in which the 



