ON GEOLOGICAL TIME. 49 



emitted ten, twenty, a hundred, perhaps a 

 thousand I won't say a hundred thousand but 

 perhaps a thousand times as much heat as would 

 be produced by all the planets falling together into 

 the sun. And yet Playfair and his followers have 

 totally disregarded this prodigious dissipation of 

 energy. He speaks of the existing state of things 

 as if it must or could have been perennial. 



23. Now, if the sun is not created a miraculous 

 body, to shine on and give out heat for ever, we 

 must suppose it to be a body subject to the laws 

 of matter (I do not say there may not be laws 

 which we have not discovered), but, at all events, 

 not violating any laws we have discovered or 

 believe we have discovered. We must deal with 

 the sun as we should with any large mass of 

 molten iron, or silicon, or sodium. We do not 

 know whether there is most of the iron, or the 

 silicon, or the sodium certainly there is sodium ; 

 as I learned from Stokes before the end of 

 the year 1851 ; and certainly, as Kirchhoff has 

 splendidly proved, there is iron. But we must 

 reason upon the sun as if it were some body 



VOL. II E 



