Read this passage from "The Obligation to Endure": It took hundreds of millions of years to produce the life
that now inhabits the earth - eons of time in which that
developing and evolving and diversifying life reached a
state of adjustment and balance with its surroundings. The
environment, rigorously shaping and directing the life it
supported, contained elements that were hostile as well as
supporting. Certain rocks gave out dangerous radiation;
even within the light of the sun, from which all life draws its
energy, there were short-wave radiations with power to
injure.
How does Carson develop the tone in this passage?