xiv aggregates: this touches on the very nature of things. The concept
of statistical symmetry which Loeb develops is particularly important,
it emphasizes the limitations in seemingly random aggregates and for
permits general statements of which the crystallographer's sym- metries
are only special cases. The reductionist and holistic approaches to the
world have been at war with each other since the times of the Greek
philosophers and before. In nature, parts clearly do fit together into
real structures, and the parts are affected by their environment. The
problem is one of understanding. The mystery that remains lies largely
in the nature of structural hierarchy, for the human mind can examine
nature on many different scales sequentially but not simultaneously.
Arthur Loeb's monograph is a fundamental one, but one can sense a devel-
opment from the relations between his zero-and three-dimensional cells
to the far more complex world of organisms and concepts. It is structure
that makes the difference between a cornfield and a cake, between an
aggregate of cells and a human being, between a random group of human
beings and a society. We can perceive anything only when we perceive its
structure, and we think by structural analogy and comparison. Several
books have been published showing the beauty of form in nature. This one
has the beauty of a work of art, but it grows out of rigorous
mathematics and from the simplest of bases-dimensional- ity, extent and
valency.