ely for
us; it is of all the colours mixed together, which, seen in a mass, make
the effect of white light. Now, objects on earth are only either seen by
the reflected light of the sun or by some artificial light. They have no
light of their own. Put them in the dark and they do not shine at all;
you cannot see them. It is the sun's light striking on them that makes
them visible. But all objects do not reflect the light equally, and this
is because they have the power of absorbing some of the rays that strike
on them and not giving them back at all, and only those rays that are
given back show to the eye. A white thing gives back all the rays, and
so looks white, for we have the whole of the sun's light returned to us
again. But how about a blue thing? It absorbs all the rays except the
blue, so that the blue rays are the only ones that come back or rebound
from it again to meet our eyes, and this makes us see the object blue;
and this is the case with all the other colours. A red object retains
all rays except the red, which it sends back to us; a yellow object
gives back only the yellow rays, and so on. What an extraordinary and
mysterious fact! Imagine a brilliant flower-garden in autumn. Here we
have tall yellow sunflowers with velvety brown centres, clustering pink
and crimson hollyhocks, deep red and bright yellow peonies, slender
fairy-like Japanese anemones, great bunches of mauve Michaelmas daisies,
and countless others, and mingled with all these are many shades of
green. Yet it is the light of the sun alone that falling on all these
varied objects, makes that glorious blaze of colour; it seems
incredible. It may be difficult to believe, but it is true beyond all
doubt. Each delicate velvety petal has some quality in it which causes
it to absorb certain of the sun's rays and send back the others, and its
colour is determined by those it sends back.

Well then how infinitely varied must be the colours hidden in the sun's
light, colours which, mixed all together, make white light! Yes, this is
so, for all colours that we know are to be found there. In fact, the
colours that make up sunlight are the colours to be seen in the rainbow,
and they run in the same order. Have you ever looked carefully at a
rainbow? If not, do so at the next chance. You will see it begins by
being dark blue at one end, and passes through all colours until it gets
to red at the other.

We cannot see a rainbow every day just when we want