I like to compare evolution to the weaving of
a great tapestry. The strong unyielding warp of this tapestry is formed by the essential nature of
elementary non-living matter, and the way in which this matter has been brought together in the evolution of our planet.
In building this warp the second law of thermodynamics has played a predominant role.
The multi-colored woof which forms the detail of the tapestry I like to think of as having been woven
onto the warp principally by mutation and natural selection.
While the warp establishes the dimensions and supports the whole,
it is the woof that most intrigues the aesthetic sense of the student of organic evolution,
showing as it does the beauty and variety of fitness of organisms to their environment.
But why should we pay so little attention to the warp, which is after all a basic part of the whole structure?
Perhaps the analogy would be more complete if something were introduced that is
occasionally seen in textiles—the active participation of the warp in the pattern itself.
Only then, I think, does one grasp the full significance of the analogy.