viii PREFACE 



knowledge," wrote Thomas Henry Huxley, "which is the chief char- 

 acteristic of our age, is affected in various ways. The main army of 

 science moves to the conquest of the new worlds slowly and surely, 

 nor ever cedes an inch of the territory gained. But the advance is 

 covered and facilitated by the ceaseless activity of clouds of light 

 troops provided with a weapon — always efficient, if not always an arm 

 of precision — the scientific imagination. It is the business of these 

 enfants perdus of science to make raids into the realms of ignorance 

 wherever they see, or think they see, a chance ; and cheerfully to ac- 

 cept defeat, or it may be annihilation, as the reward of error. Un- 

 fortunately the public, which watches the progress of the campaign, 

 too often mistakes a dashing incursion . . . for a forward move- 

 ment of the main body ; fondly imagining that the strategic movement 

 'to the rear, which occasionally follows, indicates a battle lost by 



science." 



It is regrettable that Huxley was compelled to use the metaphor of 

 a battle in describing the general advance of scientific knowledge; 

 how much better it would have been if he could have used a scientific 

 word like enzyme or catalyst in referring to those courageous men of 

 the laboratory and the field who went forth alone with instruments to 

 discover things as they really are and changed fields of knowledge 

 through their discoveries. But if he had employed these scientific 

 terms, no one, apart from the select company of scientists themselves 

 who have had to evolve a special language of their own to express 

 new matters and new meanings, would understand him. People who 

 use strange tongues are always suspect to the populace. If science is 

 to be "understanded" by the people, the people's language must be 

 used. Fortunately, for the sake of science, scientists themselves are 

 now keenly aware of the necessity of presenting their findings in 

 language which may be understood by the ordinary man. Huxley 

 himself made the liaison in his age, an age in which battles were 

 highly idealised. His grandson, however, speaking to our age, re- 

 phrases the idea in a mode more acceptable to us : "Each science or 

 branch of science seems roughly to go through three main phases in its 

 development. There is first a preliminary phase in which miscellan- 

 eous sporadic knowledge is amassed and is dated; theories are pur- 

 sued, often to be proved valueless. There then comes a classic or 

 heroic age, in which a general principle of firmly interrelated princi- 



