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the: story of the: oak trFF 
pearing out of the clear sky! Every animal is born 
from a parent animal, every plant from a parent plant, 
every child from its mother, just as every cell comes 
from another cell. 
You understand, now, how important the cell is. You 
understand, too, how each of your natural acts—when 
you breathe, or digest food, or give off waste, or move, 
or grow—each of these acts, which is shared by all living 
things, is just your cells expressing themselves in team¬ 
work. Each cell, each mass of cells, is doing the work 
for which it is fitted. 
Each special cell has its own special work, yet there is 
one thing they all do, one task they are all busy per¬ 
forming day and night, in Springtime and in Wintertime. 
Just as surely as you breathe, so surely do the cells of 
your body build up and break down, build up and break 
down, build up and break down. They absorb food, or 
water, or air, depending upon what kind of cells they are; 
they change this food or water or air into something more 
useful to them, and then they get rid of what is left. 
They build up and break down, they take in and get rid 
of, they absorb and give off. I have said it three ways— 
there are other ways to express it; try if you can think 
of one; try to say it in your own words.But 
whatever way we describe it, this building up and break¬ 
ing down, this breaking down and renewing, is called 
