vi PREFACE 



existence of anything which is beyond the horizon of his 

 understanding because he cannot make it harmonise with 

 his accepted opinions is as credulous as he who believes 

 everything without any discrimination. Either of these 

 persons is not a freethinker, but a slave to the opinions 

 which he has accepted from others, or which he may have 

 formed in the course of his education, and by his special 

 experiences in his (naturally limited) intercourse with the 

 world. If such persons meet with any extraordinary fact 

 that is beyond their own experience, they often either 

 regard it with awe and wonder, and are ready to accept 

 any wild and improbable theory that may be ofifered to 

 them in regard to such facts, or they sometimes reject 

 the testimony of credible witnesses, and frequently even 

 that of their own senses. They often do not hesitate to 

 impute the basest motives and the most silly puerilities to 

 honourable persons, and are credulous enough to believe 

 that serious and wise people had taken the trouble to 

 play upon them "practical jokes," and they are often 

 willing to admit the most absurd theories rather than to 

 use their own common sense. 



It seems almost superfluous to make these remarks, as 

 perhaps none of our readers will be willing to be classified 

 into either of these two categories; but nevertheless the 

 people to whom they may be applied are exceedingly 

 numerous, and by no means to be found only among the 

 ignorant and uneducated. On the contrary, it seems 

 that now, as at the time of the great Paracelsus, the three 

 (dis)graces of dogmatic science — self-conceit, credulity, 

 and scepticism — go still hand in hand, and that their 

 favourite places of residence are public auditories and 

 the private visiting-rooms of the learned. 



It is difficult for the light of truth to penetrate into a 



