121. But note that porosity is not the same as permeability, which measures the ease with which water can flow through a material; this depends on the sizes of the individual cavities and the crevices linking them.
122. Much of the water in a sample of water-saturated sediment or rock will drain from it if the sample is put in a suitable dry place.
123. It is held there by the force of surface tension without which water would drain instantly from any wet surface, leaving it totally dry.
124. The total volume of water in the saturated sample must therefore be thought of as consisting of water that can, and water that cannot, drain away.
125. If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.
126. The most widely accepted theory, championed by anthropologists in the late nineteenth and early twentieth century, envisions theater as emerging out of myth and ritual.
127. Having little understanding of natural causes, it attributes both desirable and undesirable occurrences to supernatural or magical forces, and it searches for means to win the favor of these forces.
128. Perceiving an apparent connection between certain actions performed by the group and the result it desires, the group repeats, refines and formalizes those actions into fixed ceremonies, or rituals.
129. But the myths that have grown up around the rites may continue as part of the group’s oral tradition and may even come to be acted out under conditions divorced from these rites.
130. When this occurs, the first step has been taken toward theater as an autonomous activity, and thereafter entertainment and aesthetic values may gradually replace the former mystical and socially efficacious concerns.
