Today, I prepare for Christmas. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
Thirty-five years ago, I
heard the pastoral theologian Bob Rodenmayer preach
on Christmas Eve. He called Christmas the "Great
Watershed of History." The phrase stayed with me.
It's a notion that keeps yielding up new insights.
A watershed is a region where all rain gathers into
the same outlet river. Rodenmeyer meant that every
event before the first Christmas had gone one way.
Every event that followed would flow another way
Years later I sat in a lecture on rainfall runoff.
As I listened, that Christmas image came back. I
thought about the insistence of gravity. I saw
drops rolling off leaves and twigs to join one
another. Trickle joining trickle to form rivulets.
Rivulets merging into streams and streams into
Suddenly the penny dropped. I realized that
raindrops find their way to the river the same way
molecules seek their energy levels. By nightfall, I
had a new theory of rainfall runoff. In an odd leap
of the mind, I made the watershed into a
thermodynamic system. It may've been the most
creative thing I ever did.
And so each Christmas I think about watersheds. I
think about those instants when our lives change --
when the flow of events diverts to an entirely new
Your Christmas may be a secular holiday. It may be
a holy feast day. Either way, it signals watershed.
Christmas cannot help but promise change, renewal,
and mystery as well.
Every creative act contains those same elements --
change, renewal, and mystery. Every creative act is
a watershed that alters our life irrevocably. Every
creative act holds that Christmas sense of
potential change and birth pain.
This is the season when depression and despair
rise. But only when we give up hope of crossing any
watershed. Poet Carol Drake anticipates Christmas
with the words, "joy and terror in the winter
night." She reminds me that my worst Christmasses
are the static ones -- the ones when I fail to
stand in awe of impending change.
This year the incipience is electric. I mean for
the events in my life to merge and flow into some
new, untraveled river. And that's my Christmas wish
for you. I wish you pain and joy, growth and
change. I wish you disruption and renewal.
I wish you a moment in your own history when you
turn from one thing into another. I wish that you
might find your creative center. I wish that you
might cross the great watershed in your own life
and emerge as a new being.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
The complete poem by Carol Christopher Drake is the
text of Hymn Number 69 in the 1982 Episcopal
Hymnal. She, as it just so happens, listened
to the same Christmas sermon I cite here.
The thermodynamic analysis of rainfall runoff is
developed in the following four papers.
Lienhard, J.H., A Statistical Mechanical Prediction
of the Dimensionless Unit Hydrograph. J.
Geophys. Res, Vol. 69, No. 24, Dec. 1964, p.
Lienhard, J.H., and Meyer, P.L., A Physical Basis
for the Generalized Gamma Distribution. Q.
App. Math, Vol. 25, No. 3, 1967, p. 330.
Lienhard, J.H., and Davis, L.B., Jr., An Extension
of Statistical Mechanics to the Description of a
Broad Class of Macroscopic Systems. Zeit. f.
Ang. Math. u. Mech, (ZAMP), Vol. 22, No. 1,
1971, p. 85.
Lienhard, J.H., On The Prediction of the
Dimensionless Unit Hydrograph, Nordic
Hydrology, Vol. 3, 1972, pp. 107-109.
Two figures from the first reference above: Left: a
typical Illinois watershed. Right: predicted and
observed rainfall runoff following a sudden storm
upon that watershed
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
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