58 
matter? Newton suggests that ether is donsor °ntnde of 
solids, and less dense within them. This would imply that thy 
exert on each other a repulsive power. But Mosotti, Norto , 
and most other modern theorists, make the mutual actio 
attractive, so that it would be denser within bodies, and a 
their surface, than in free space. . , i 
Once more, if the ether is self-repulsive, and intensely 
elastic, how is this elasticity maintained ? Must it not diffuse 
itself into empty space ? Or are we to conceive the umveise 
bounded by a solid wall, able to resist an almost infinite pres- 
sure ? Sir John Herschel has remarked : “ Under no concep- 
tion but that of a solid can an elastic and expansible medium 
be self-contained. If free to expand, it would require a bounc - 
ins; envelope of sufficient strength to resist its outward pres- 
sure. To evade this by supposing it infinite m extent, is to 
meet the difficulty by words without ideas, and to take reiuge 
in a negation of that which constitutes the difficulty. 
Thus from Newton to the present day, all these various 
doctrines about ether have been held by men of eminence >; 
that there is no such ether distinct from matter, that there are 
two kinds, or many, each rarer than the one before it, or on 
kind alone ; that it is a solid and a fluid, attractive and lepu - 
sive, a continuous plenum, or made up of discontinuous atoms ; 
that these are solid and finite, or points and force-ccntrcsoiiy, 
that it is attracted by matter, that it is repelled by it, and that 
it is neither attracted nor repelled, but merely is shut out 
from the space which matter occupies; that it is finite m extent, 
and that is infinite, a repulsive variety of material substance, 
or a bridge between the visible worlds and an unseen universe. 
Physical science, with regard to the nature of matter ant 
ether, its two constituent elements, is thus in its merest 
childhood. It has yet to decide which is true out of a dozen 
or a score of rival theories. Its teachers, then, and sti 
more its disciples, will do wisely to assume a far more modest 
tone in dealing with moral and religious questions than 
has been their practice of late years. _ It is ridiculous for 
those to declaim on the diversity of religious creeds, and t he 
controversies and strifes of theologians, who can hardly agree 
in laying a single stone in the foundations of their own phi o- 
S ° IV. The Conservation of Energy, the Doctrine ol Evolution, 
and the Nebular Theory, aro so closely related that it will be 
better to examine them together. The great divergence among 
scientific theorists, and the large amount of what is doubttul 
or untrue in their reasonings will thus be seen m a clearer 
