at the composition of animal
bodies is identical with that of vegetable; that there is nothing in one
that is not in the other; and yet, behold the difference! a difference
beyond the reach of chemistry to explain. Biology can tell us all about
these differences and many other things, but it cannot tell us the
secret we are looking for,--what it is that fashions from the same
elements two bodies so unlike as a tree and a man.

Decay and disintegration in the inorganic world often lead to the
production of beautiful forms. In life the reverse is true; the vital
forces build up varied and picturesque forms which when pulled down are
shapeless and displeasing. The immense layers of sandstone and limestone
out of which the wonderful forms that fill the Grand Canon of the
Colorado are carved were laid down in wide uniform sheets; if the waters
had deposited their material in the forms which we now see, it would
have been a miracle. We marvel and admire as we gaze upon them now; we
do more, we have to speculate as to how it was all done by the blind,
unintelligent forces. Giant stairways, enormous alcoves, dizzy, highly
wrought balustrades, massive vertical walls standing four-square like
huge foundations--how did all the unguided erosive forces do it? The
secret is in the structure of the rock, in the lines of cleavage, in the
unequal hardness, and in the impulsive, irregular, and unequal action of
the eroding agents. These agents follow the lines of least resistance;
they are active at different times and seasons, and from different
directions; they work with infinite slowness; they undermine, they
disintegrate, they dislodge, they transport; the hard streaks resist
them, the soft streaks invite them; water charged with sand and gravel
saws down; the wind, armed with fine sand, rounds off and hollows out;
and thus the sculpturing goes on. But after you have reasoned out all
these things, you still marvel at the symmetry and the structural beauty
of the forms. They look like the handiwork of barbarian gods. They are
the handiwork of physical forces which we can see and measure and in a
degree control. But what a gulf separates them from the handiwork of the
organic forces!

VI

Some things come and some things arise; things that already exist may
come, but potential things arise; my friend comes to visit me, the tide
comes up the river, the cold or hot wave comes from the west; but the
seasons, night and morning, health