tablecloth while you would not be able to distinguish a black
object, because the few faint rays that are there, are all sent
back to you from a white surface.

Is it not curious to think that there is really no such thing as
colour in the leaf, the table, the coat, or the geranium flower,
but we see them of different colours because, for some reason,
they send back only certain coloured waves to our eye?

Wherever you look, then, and whatever you see, all the beautiful
tints, colours, lights, and shades around you are the work of the
tiny sun-waves.

Again, light does a great deal of work when it falls upon plants.
Those rays of light which are caught by the leaf are by no means
idle; we shall see in Lecture VII that the leaf uses them to
digest its food and make the sap on which the plant feeds.



Week 6

We all know that a plant becomes pale and sickly if it has not
sunlight, and the reason is, that without these light-waves it
cannot get food out of the air, nor make the sap and juices which
it needs. When you look at plants and trees growing in the
beautiful meadows; at the fields of corn, and at the lovely
landscape, you are looking on the work of the tiny waves of
light, which never rest all through the day in helping to give
life to every green thing that grows.