IV PREFACE. 



protected from the influence of imposture, and verification 

 applied in defeating or exposing delusion. 



Much of the ease with which we are deceived by the 

 phenomena of natural magic arises from our want of 

 previous preparation, and our deficient knowledge, for the 

 moment, of the laws within which the true explanation of 

 these phenomena may be found. Hence, very much in pro- 

 portion to our ready knowledge or intelligence we are 

 either credulous or sceptical the words are used in a philo- 

 sophic sense merely ; and history has shown that men are 

 often quite as far from the truth in the extremity of their 

 scepticism as they are in the extreme of credulity itself. 

 Mere scepticism has in fact been a great barrier and 

 enemy to the progress of science ; and though the credulous 

 have often sunk into superstition and become intolerant, 

 they have more generally recognized than ignored those 

 temporarily incomprehensible facts which the advent of 

 calm science has satisfactorily explained. Indeed, but 

 for this slight difference, these two extremes only too 

 often meet ; for the extreme of scepticism is credulity, and 

 the extreme of credulity, or superstition, is scepticism. 

 Both distrust truth ; both trust their own prejudices and 

 impressions rather than truth ; both misrepresent and 

 persecute it ; both obstruct the progress of its intelligible 

 development. Even in this day many facts of science 

 are, in consequence, left, without examination, in the hands 

 of charlatans whose function always is to render them 

 odious by exaggeration and therefore repugnant to 

 scientific study and explanation ; for the scientific rnind 

 ever recoils from the wares of the quack, and too nastily 

 ignoring the small grain of genuine and philosophic truth 

 which is necessary and almost in every case present to 

 sustain any enduring pretension considers the whole 

 elements involved to be as much matters of imposture as 

 the individual by whom they arc employed. This is 



