PEEFACE 



In Central Asia, near the river Oxus, theie is 

 said to be a famous lock, called the Lamp Bock, 

 from a strange light that seems to issue from a cav- 

 ern far up on the side of the mountain. The nar 

 tives have a superstitious fear of the rock, and 

 ascribe the light to some dragon or demon that 

 lives in the cave. Kecently a bold English trav- 

 eler climbed up and investigated the phenomenon. 

 The light was found, after all, to be only the light 

 of common day. The cave proved to be a tunnel, 

 and the mysterious light came through the rock 

 from the other side, making a strong glow or nim- 

 bus at the mouth of the dark cavern. 



This incident, so typical of much that has taken 

 place and is still taking place in the world, espe- 

 cially in the religious experience of mankind, has 

 suggested the title to this volume of essays, in which 

 I have urged the sufficiency and the universality of 

 natural law, and that most of the mysterious lights 

 with which our fears, our ignorance, or our super- 

 stitions have invested the subject of religion, when 

 brought to the test of reason, either vanish entirely 

 or give place to the light of common day. 



The essays for the most part were written twelve 

 or fifteen years ago, when the author's mind was 



