18 THE PKOGEESS AND SPIEIT OF 



creation in which all human knowledge ends ? These and 

 other like questions belong to the philosophy of our day ; 

 some of them shadowed out in the hypotheses of antiquity ; 

 now approached through the safer avenues of experiment and 

 sound induction. How far these may lead us to the future 

 more complete solution of the problems suggested we cannot 

 here stop to enquire. 



In passing from the province of Forces acting on matter, 

 to that of Matter thus acted on, we have yet to traverse 

 another debateable ground, on which science is seeking to find 

 some firm footing, as well in explanation of known phenomena 

 as for purposes of further research. We allude here to the 

 question regarding the physical condition of space itself '; 

 of those inter-planetary and inter-sidereal distances, some of 

 them hardly measurable by numbers, and such, in truth, as 

 no effort of mind can compass or conceive. Are we to regard 

 this vastness of space as void of matter a mere vacuum, 

 through which the numberless worlds we see as stars or 

 planets are dispersed ? Or may we better contemplate it as 

 pervaded throughout by some material medium, though so 

 rare and attenuated, that no form of matter of which our 

 senses are cognisant can rightly interpret it to our reason ? 

 The question must no longer be argued in that mystical 

 language of ( nature abhorring a vacuum,' which satisfied the 

 demands of an earlier philosophy. Nor can we evade it by 

 the adoption of terms such as ether, ethereal medium, &c., 

 which, though sanctioned by some great names, go little 

 further than to shelter a vague and incomplete solution. 

 Modern science seeks urgently for proof that matter, in some 

 condition, does exist throughout space ; and in such con- 

 tinuity, however rare it be, that forces may be transmitted by 

 or through the medium thus afforded. Two great powers, 

 gravitation and light, undoubtedly reach us from the most 



