What is the key passage in Fahrenheit 451?

A key passage that grasps more than one theme of the book
is near the end when Granger and Montag are speaking.  The passage begins, "Granger
stood looking back with Montag."  It ends with, "The lawn cutter might just as well not
have been there at all; the gardener will be there a lifetime."  In the passage, Granger
talks about how his grandfather said every person should leave something behind him when
he dies, some benefit to the welfare of others.  The story deals to a great extent with
the passivity of the people in the society.  They don't care about much except for
themselves.  This is seen in Mildred, her friends, the way kids kill kids according to
the description Clarisse gives Montag.  The lawncutter is passive; his actions do not
bring about any significant change.  The gardener, on the other hand, creates something
which is a positive change.  The passage also addresses the theme of change and
transformation. The lawncutter does not bring about change, but the gardener does.  The
gardener transforms his plot of earth from nothing more than dirt and weeds to something
that can nourish and sustain people.