THE CONSTITUTION OF MATTER. 15 
taste, smell, light, or sound, is a phenomenon of psycho- 
logical reaction which occurs in the soul when it is teased 
with a certain degree of energy by nerve-action, which in 
its turn depends on an outward action; but there is no re- 
lation of resemblance between the latter and the sensation 
it provokes. The ether, which, by its vibrations in unison 
with the elements of our retina, produces sensations of 
light in us, has in itself no luminosity. The proof of this 
is, that two rays of light meeting under certain conditions 
may annul each other, and produce darkness. Now, Magy 
maintains that the subjectivity of extension is of the same 
order with that of light. Extension in general is explained 
by purely dynamic reasons, as readily as that particular 
extension is which serves as a kind of support for luminous 
phenomena, which evidently result from vibrations of the 
unextended principles. Helmholtz, in his latest writings, 
fully adopts this doctrine of corporeal extension. 
We thus see that there is no difficulty in reconciling ex- 
tension with unextended forces, and the phenomena of ex- 
tension with principles of action; but this is only the first 
part of the problem, and it becomes necessary now to as- 
cend from these unextended forces and active principles to 
those more or less complex manifestations which make up 
the infinite universe, adorning space with imperishable 
variety. Let usimagine this universe filled with the great- 
est conceivable number of active principles, all identical, 
diffused uniformly throughout immensity, and consequently 
in a state of perfect equilibrium. All will be torpid in ab- 
solute repose, in which form without shape and force with- 
out spring will be as though they were not. Between a 
homogeneous, motionless substance, identical with itself 
throughout space at all points, and nihility, reason per- 
ceives no difference. In such a system, nothing has weight, 
for there is no attracting centre; heat is no more possible 
for it than light, since these two forms of energy are bound 
