INTRODUCTORY 5) 
case where bad fortune followed would be sure to out- 
weigh a hundred where nothing happened, and though you 
might convince yourself of the falseness of the story, you 
would not influence those who held the belief before. 
Another idea I want you to keep constantly before 
you is the essential unity of all plant life. When one 
studies individuals separately one is apt to see only 
the differences, and forget what they have in common, 
but both sides are of equal importance to keep in view. 
The great glory of Charles Darwin was that he insisted 
on this close connection, and constantly endeavoured to 
look on Nature as a whole. The chief interest of Natural 
. History les in watching the development from a lower 
form to a higher, and tracing the first appearance of a 
new function or instrument in its simplest form, which 
is afterwards to become of the highest importance. From 
the oak to the mushroom, and even lower, to the micro- 
scopic plants, such as yeast, there is a ladder of descent 
in which, it is true, many rungs are missing, but by 
passing along which we may come to a better under- 
standing. 
Again, we shall see how the whole group of plants of 
every kind have close relations with the rest of nature. 
All animals depend on them, directly or indirectly, for 
their nourishment, including ourselves. It is only plants 
that can take up sufficient food from the earth. We must 
either eat vegetables or animals, such as cows and sheep, 
that in their turn have eaten them, and have made them 
into flesh. Without flowers, also, we should have no 
butterflies and no bees, none of our fairest insects, for 
they are dependent on the honey, and in their turn, as 
_ we shall see later, they are necessary to the flowers for 
; _ the securing of seeds. 
