higher and higher forces took a hand in the game. First its elements
passed through the stage of fire, then through the stage of water,
then merged into the stage of air. More and more the aerial
elements--oxygen, carbon, nitrogen--have entered into its
constituents and fattened the soil. The humanizing of the earth has
been largely a process of oxidation. More than disintegrated rock
makes up the soil; the air and the rains and the snows have all
contributed a share.

The history of the soil which we turn with our spade, and stamp with
our shoes, covers millions upon millions of years. It is the ashes
of the mountains, the leavings of untold generations of animal and
vegetable life. It came out of the sea, it drifted from the heavens;
it flowed out from the fiery heart of the globe; it has been worked
over and over by frost and flood, blown by winds, shoveled by ice,
--mixed and kneaded and moulded as the house-wife kneads and moulds
her bread,--refining and refining from age to age. Much of it was
held in solution in the primordial seas, whence it was filtered and
used and precipitated by countless forms of marine life, making a
sediment that in time became rocks, that again in time became
continents or parts of them, which the aerial forces reduced to
soil. Indeed, the soil itself is an evolution, as much so as the
life upon it.

We probably have little conception of how intimate and cooperative
all parts of the universe are with one another,--of the debt we owe
to the farthest stars, and to the remotest period of time. We must
owe a debt to the monsters of Mesozoic and Caenozoic time; they
helped to fertilize the soil for us, and to discipline the ruder
forces of life. We owe a debt to all that has gone before: to the