30 FROM NEBULA TO NEBULA 



much as suggested the utilisation of the energy inherent 

 in our cosmic fall to account for the gyrations of the 

 planets and satellites, and especially for their multitudi- 

 nous concordances. Following the lead of Newton, one 

 after another of them has fallen blindly into line and kept 

 in the same old rut. Newton, of course, is more to be ex- 

 cused than the rest ; for he was not in possession of cer- 

 tain essential factors, and, besides, he was so far ahead of 

 his own generation that not even his modest postulate 

 that gravitation extends as far as the moon was accepted 

 by it during his lifetime, though he survived, as was 

 stated before, the publication of his Principia for as much 

 as four decades. The oversight, futhermore, appears all 

 the greater when we remember with what assiduity 

 mathematicians have devoted themselves to the investiga- 

 tion of the purely academical and altogether speculative 

 " fourth dimension of space ", the while remaining stone 

 blind to this genuine third dynamical dimension of the 

 real cosmos. To them, just as to Newton, the solar sys- 

 tem is, to all intents and purposes, a world of two dimen- 

 sions, in which the mutual attractions of the members 

 take place in a single plane, the plane of the ecliptic ; and 

 they seem never to have taken thought to look up or down 

 from that level in search of an extraneous motive power 

 acting transversely. The universe of Newton's concep- 

 tion lacked the dynamical dimension of THICKNESS. 



I trust that I have now said enough to convince the 

 unprejudiced reader that there is plenty of room for im- 

 provement in the theory of astronomy as now taught in 

 the schools, and to prepare his mind to receive new im- 

 pressions and reconsider past judgments. 



When, at the age of twenty-three, as the story goes, 

 Newton saw the apple fall, the thought that occurred to 

 him was not single but duplex. One phase of it was, 

 Does the force of gravitation extend as far as from the 

 earth to the moon?, and the other, If it does so extend, 

 then why does the moon not fall, but preserve its uniform 

 distance from age to age! Doubtless thousands of men be- 



