SUNBEAMS AND THEIR WORK. 45 
you mean that the leaf does not want the green waves 
of the sunbeam, but sends them back to you. In the 
same way the scarlet geranium rejects the red waves ; 
this table sends back brown waves ; a white tablecloth 
sends back nearly the whole of the waves, and a black 
coat scarcely any. This is why, when there is very 
little light in the room, you can see a white 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 Lec- 
ture VII that the leaf uses them to digest its food and 
make the sap on which the plant feeds. 
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 land- 
scape, you are looking on the work of the tiny waves 
of light, which never rest all through the day in help- 
ing to give life to every green thing that grows. 
