16 AN INTRODUCTION TO SCIENCE 



gravitations are proportional to the quantity of matter in 

 that other body, and inversely proportional to the square of 

 the distance from it." But this is not an explanation of the 

 nature of gravitation, still less is it an explanation of its 

 cause. It is merely the collection of like phenomena into a 

 single group. As knowledge progresses other phenomena 

 will be seen to illustrate the law of gravitation, or will 

 demand inclusion with those phenomena which \ve have 

 already enumerated in a common law. Hydrogen gas, when 

 liberated into the atmosphere, is not attracted by the mass of 

 the earth ; on the contrary, it escapes from our atmosphere 

 and flies off into space. But this does not invalidate the 

 law of gravitation. The falling of a stone to the earth and 

 the flying away from the earth of hydrogen gas must be 

 ultimately due to a common cause. It is conceivable that 

 some day the "law of gravitation" will be enlarged until 

 its formula includes these apparently opposite phenomena, 

 in which case it is not unlikely that scientific writers will 

 find that the law in its new form is too wide for useful appli- 

 cation. The phenomena which it comprises will be seen to 

 fall into two or more groups, the members of each of which 

 have more in common with one another than they have with 

 those in the other groups. New proximate laws will then be 

 formulated within the law of gravitation. The docket " law 

 of gravitation" will be subdivided, and the new dockets will 

 include a greater number of phenomena than the " law " as 

 now formulated can be made to do. 



Not only did the writer of " Natural Law in the Spiritual 

 World" mistake the meaning and value of law, but he was 

 curiously obtuse to the trend of his own arguments. He 

 found that an investigation of the spiritual world, as Chris- 

 tians understand it, shows that its "laws" are similar to 

 those which man has formulated for the' phenomena of 

 nature. Mr. Drummond found that in the supernatural world 

 as revealed in the Bible, the laws with which we are familiar 

 in the physical world hold sway. Had he found other laws 



