he terms in
which they are taught, I neither accept, nor assail, the
conclusions respecting the oscillatory states of light, heat, and
sound, which have resulted from the postulate of an elastic, though
impalpable and imponderable ether, possessing the elasticity of
air. This only I desire you to mark with attention,--that both
light and sound are _sensations_ of the animal frame, which remain,
and must remain, wholly inexplicable, whatever manner of force,
pulse, or palpitation may be instrumental in producing them: nor
does any such force _become_ light or sound, except in its
rencontre with an animal. The leaf hears no murmur in the wind to
which it wavers on the branches, nor can the clay discern the
vibration by which it is thrilled into a ruby. The Eye and the Ear
are the creators alike of the ray and the tone; and the conclusion
follows logically from the right conception of their living
power,--"He that planted the Ear, shall He not hear? He that formed
the Eye, shall not He see?"

For security, therefore, and simplicity of definition of light, you
will find no possibility of advancing beyond Plato's "the power
that through the eye manifests color," but on that definition, you
will find, alike by Plato and all great subsequent thinkers, a
_moral_ Science of Light founded, far and away more important to
you than all the physical laws ever learned by vitreous revelation.
Concerning which I will refer you to the sixth lecture which I gave
at Oxford in 1872, on the relation of Art to the Science of Light
('The Eagle's Nest'), reading now only the sentence introducing its
subject:--"The 'Fiat lux' of creation is therefore, in the deep
sense, 'fiat anima,' and is as much, when you understand it, the
ordering of Intelligence as the ordering of Vision. It is the
appointment of change of what had been else only a mechanical
effluence from things unseen to things unseeing,--from Stars, that
did not shine, to Earth, that did not perceive,--the change, I say,
of that blind vibration into the glory of the Sun and Moon for
human eyes: so making possible the communication out of the
unfathomable truth of that portion of truth which is good for us,
and animating to us, and is set to rule over the day and over the
night of our joy and our sorrow."

Returning now to our subject at the point from which I permitted
myself, I trust not without your pardon, to diverge; you may
incidentally, but carefully, observe, that the effect