ESSAY-REVIEWS 99 



for it on inductive grounds the overwhelming certainty which 

 Dr. Johnstone confers upon it by means of deduction. To 

 most physicists the validity of the law is based upon the 

 unbroken experience of mankind ; and that experience, though 

 it may bestow a very high degree of probability, does not rise 

 to the attenuated regions of co 00 : 1. It would have been simpler 

 and much more convincing to say that, as the second law of 

 thermodynamics is based only on finite experience in a very 

 limited time, it may possibly not hold good everywhere, and 

 may not have held good in past times. 



Let us pass, however, to the conclusion of Dr. Johnstone's 

 physical deduction. Let us suppose that energy is and has 

 always been degraded throughout infinite time. Yet we see 

 concentrated forms of energy still in existence : are we then 

 bound to infer that "there must be a restoration of available 

 energy"? Certainly not. Dr. Johnstone is fond of dealing in 

 infinities ; let us add one more. Let us suppose that the energy 

 in the universe is, like time and space, also infinite — an entirely 

 reasonable hypothesis. Then even the lapse of infinite time 

 would not involve the extinction of all differences of energy- 

 potential. Dr. Johnstone's argument is only sound (even in 

 appearance) on the assumption that the universe is limited; but 

 that surely far exceeds our possible knowledge. We know our 

 own world and solar system ; we behold in the inconceivable 

 depths of the universe other worlds and solar systems much 

 like our own. May not these worlds extend right away to the 

 uttermost limits of conceivability ? What right has Dr. John- 

 stone to assume that space is infinite and that the universe is 

 finite ? Does he suppose that " the universe " — the great stellar 

 systems which are disclosed by powerful telescopes — are a dot 

 in the midst of infinite and empty space ? They may be, but 

 how does he know ? How can he venture to found a theory 

 of life upon such an assumption ? We know that light travels 

 with a velocity of about 186,000 miles a second. We know that 

 there are stars so remote that the light which they emitted 

 when Christ was alive is only now reaching us. The space 

 which separates us from those stars dwindles to a mathematical 

 point when looked at from the standpoint of infinite space. 

 If we represent that vast distance on a star-map by a space 

 of one inch, there may, for all we know, be other stars at a 

 distance which we should have to represent on the same scale 



