337 
that the notion of the existence of a luminiferous ether, capable 
by its vibrations (and perhaps in other ways) of affecting the 
relations of ponderable matter has become essential to the 
thoughts of the modern chemist. 
40. The Professor says : “ Euler established the principle 
that a substance absorbs all those rays of light with whose rate 
of vibrations the vibrations of its smallest particle can agree. 
“ Each molecule of a substance, according to its chemical 
structure, has certain determinate rates of vibration . If it is 
struck by a wave [of ether] whose 'period agrees with one of 
those proper to itself ‘ it is set in motion , or has its motion 
strengthened if it has already been vibrating. The wave gives 
up its energy, wholly or partly, to the molecule, goes through 
the substance weakened, or does not go through it at all, i.e. } it 
is absorbed.” 
41. We have arrived at the conclusion (in accordance with 
the above principle) that the chlorophyll, or green of the leaves, 
derives all its power of fixing carbon, that is of growth and 
increase, from the action of the rays of light upon it. This, 
indeed, has been abundantly proved in other ways. Thus it 
has been shown, that if a tuber of potato is allowed to vegetate 
in the dark, although it puts forth leaves and shoots, and does 
its utmost (so to speak) to form a plant, yet being deficient in 
the effects of light, and consequently not assimilating carbon, 
it forms all this pseudo-growth at the expense of the substance 
stored up in the tuber, and in the end weighs no more than it 
did at the beginning. 
42. Thus, without the luminiferous ether there could be no 
light, without the vibration of its waves no vegetation, and without 
vegetation the world would be a waste, devoid of vegetable and 
consequently of animal life. 
43. All our existence here rests, then, upon a scientific fact, 
which the disciples of M. Comte are bound to reject as inca- 
pable of proof, and excluded from belief by the golden maxim, 
“ the first commandment of science.” 
Part IY. — The Spiritual World. 
44. Professor Huxley enunciates that there is a path that leads 
to truth so certainly that any one who will follow it must needs 
reach the goal, whether his capacity be great or small. And 
that there is one guiding rule by -which a man may always find 
