There is concentrated light--the very essence of light--within
ourselves, particularly in the brain, to which the light, having
travelled about the body, is conveyed, through the instrumentality of
the blood, to the nerves and other organs.
In speaking of the brain, we often use words belonging to vision. Until
the discovery of "concentrated light," we did not know how truthful were
these expressions, one of which in our language answers to the "mind's
eye." The eye as well as the brain contains concentrated light, and
physical impressions received through the visual organs are by this
electricity immediately conveyed to the sympathetic "light" of the
brain.
By the application of concentrated light we can even increase for a time
the intellectual powers, or, rather, we can strengthen the instrument
through which the intellectual powers are manifested.