The Mind and Its Education - George Herbert Betts

Let us next inquire how this mechanism of the nervous system is acted upon in
such a way as to give us sensations. In order to understand this, we must first
know that all forms of matter are composed of minute atoms which are in
constant motion, and by imparting this motion to the air or the ether which
surrounds them, are constantly radiating energy in the form of minute waves
throughout space. These waves, or radiations, are incredibly rapid in some
instances and rather slow in others. In sending out its energy in the form of these
waves, the physical world is doing its part to permit us to form its acquaintance.
The end-organs of the sensory nerves must meet this advance half-way, and be
so constructed as to be affected by the different forms of energy which are
constantly beating upon them.