462 THE WORLD MACHINE 



temperature is reached in bodies at the evolutionary stage of 

 our own sun. If this were true, the pressure of radiation from a 

 body of the conjectural dimensions of Canopus would be quite 

 insufficient to counterbalance its gravitational pull. The process 

 of aggregation might be delayed, but in the unthinkable reaches 

 of time which we are considering it would still be consummated. 

 The very acute observation that if any such process were 

 at work it would have been completed long ago, lays bare 

 the real dilemma. It is evident enough that the problem is 

 in reality transcendent. 



Such gigantesque if somewhat tenuous speculations mark in 

 some sense the highest attainments of the human mind. Re- 

 flecting upon its lowly origin considering its stumbling, groping 

 beginnings comprehending in a single sweep the tremendous 

 range of its activities we shall not err, perhaps, if we consider 

 that the true world- marvel is the mind itself. Reluctantly, 

 and with the painful sense as of a hobble cast about the feet of 

 some splendid courser, every fibre of his body trembling with the 

 excitement of the chase, we recurrently awake to the realisation 

 of its finite limitations. 



From such heights we must descend at intervals to consider 

 the rather slender foundations upon which it rests. It was 

 Hume who pointed out that all we know of cause is reiterated 

 sequence, the constant succession of events. It is this constant 

 succession which we call law. It is upon this which rests the 

 vast body of co-ordinated knowledge which we may regard as 

 in some sense permanent, an inexpugnable fortress. It is with 

 the aid of these same materials that speculatively we lift our 

 kites and aeroplanes to tour the blue above. 



But it is evident that we can have no idea as to the past, 

 no surmise as to the future, save that which is based upon the 

 supposition that this constant succession is never changed. 

 Moreover, the facts which we have to go on are as yet slight. 

 The law of gravitation is hardly more than two hundred years 

 old. The idea of conservation of energy dates back little more 

 than half a century, a couple of generations. It is only within 

 forty or fifty years that man has had any reasonable basis upon 

 which to speculate as to his origin or his future. 



This fact bids us exercise a certain, if indulgent, scepticism 

 towards any very rigid conclusions. We need not cast aside 



