inner light interpenetrate each other along the whole tract between
these two boundaries, but normally we are not conscious of this
process. We first become conscious of it where our active gaze - that
is, the inner light sent forth through the eye - reaches the limit of
its activity. At that point we become aware of the object of our gaze.
So here we find confirmed a fact noted earlier, that consciousness - at
least at its present state of evolution - arises where for some reason
or other our volition conies to rest.

*

The foregoing observations have served to awaken us in a preliminary
way to the fact that an essential part of our act of seeing takes place
outside our bodily organ of vision and that our visual experience is
determined by what happens out there between our gaze and the medium it
has to penetrate. Our next task will be to find out how this part of
our visual activity is affected by the properties of the different
colours. We shall thereby gain a further insight into the nature of the
polarity underlying all colour-phenomena, and this again will enable us
to move a step further towards becoming conscious of what happens in
our act of seeing.

We shall start by observing what happens to the two sides of the
colour-scale when the optical medium assumes various degrees of
density.

For the sky to appear blue by day a certain purity of the atmosphere is
needed. The more veiled the atmosphere becomes the more the blue of the
sky turns towards white; the purer and rarer the atmosphere, the deeper
the blue, gradually approaching to black. To mountain climbers and