d beloved by the Sun,--that fable gives you
at once the two great facts about vegetation. Where warmth is, and
moisture--there, also, the leaf. Where no warmth--there is no leaf; where
there is no dew--no leaf.

7. Look, then, to the branch you hold in your hand. That you _can_ so hold
it, or make a crown of it, if you choose, is the first thing I want you to
note of it;--the proportion of size, namely, between the leaf and _you_.
Great part of your life and character, as a human creature, has depended on
that. Suppose all leaves had been spacious, like some palm leaves; solid,
like cactus stem; or that trees had grown, as they might of course just as
easily have grown, like mushrooms, all one great cluster of leaf round one
stalk. I do not say that they are divided into small leaves only for your
delight, or your service, as if you were the monarch of everything--even in
this atom of a globe. You are made of your proper size; and the leaves of
theirs: for reasons, and by laws, of which neither the leaves nor you know
anything. Only note the harmony between both, and the joy we may have in
this division and mystery of the frivolous and tremulous petals, {44} which
break the light and the breeze,--compared to what with the frivolous and
tremulous mind which is in us, we could have had out of domes, or
penthouses, or walls of leaf.

8. Secondly; think awhile of its dark clear green, and the good of it to
you. Scientifically, you know green in leaves is owing to 'chlorophyll,'
or, in English, to 'greenleaf.' It may be very fine to know that; but my
advice to you, on the whole, is to rest content with the general fact that
leaves are green when they do not grow in or near smoky towns; and not by
any means to rest content with the fact that very soon there will not be a
green leaf in England, but only greenish-black ones. And thereon resolve
that you will yourself endeavour to promote the growing of the green wood,
rather than of the black.

9. Looking at the back of your laurel-leaves, you see how the central rib
or spine of each, and the lateral branchings, strengthen and carry it. I
find much confused use, in botanical works, of the words Vein and Rib. For,
indeed, there are veins _in_ the ribs of leaves, as marrow in bones; and
the projecting bars often gradually depress themselves into a transparent
net of rivers. But the _mechanical_ force of the framework in carrying the
leaf-tissue is the point first to be noticed;