【正文】 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 e 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.131. Although origin in ritual has long been the most popular, it is by no means the only theory about how the theater came into being.132. Thus, the recalling of an event (a hunt, battle, or other feat) is elaborated through the narrator’s pantomime and impersonation and eventually through each role being assumed by a different person.133. A closely related theory sees theater as evolving out of dances that are primarily pantomimic, rhythmical or gymnastic, or from imitations of animal noises and sounds.134. Admiration for the performer’s skill, virtuosity, and grace are seen as motivation for elaborating the activities into fully realized theatrical performances. 135. For example, one sign of this condition is the appearance of the ic vision, since edy requires sufficient detachment to view some deviations from social norms as ridiculous rather than as serious threats to the welfare of the entire group.136. For example, some early societies ceased to consider certain rites essential to their wellbeing and abandoned them, nevertheless, they retained as parts of their oral tradition the myths that had grown up around the rites and admired them for their artistic qualities rather than for their religious usefulness.137. Within a vertical distance of just a few tens of meters, trees disappear as a lifeform and are replaced by low shrubs, herbs, and grasses.138. In many semiarid areas there is also a lower timberline where the forest passes into steppe or desert at its lower edge, usually because of a lack of moisture.139. Timberline trees are normally evergreens, suggesting that these have some advantage over deciduous trees (those that lose their leaves) in the extreme environments of the upper timberline.140. This is particularly true for trees in the middle and upper latitudes, which tend to attain greater heights on ridges, whereas in the tropics the trees reach their greater heights in the valleys.141. Latelying snow reduces the effective growing season to the point where seedlings cannot establish themselves.142. Wind velocity also increases with altitude and may cause serious stress for trees, as is made evident by the deformed shapes at high altitudes.143. Some scientists have proposed that the presence of increasing levels of ultraviolet light with elevation may play a role, while browsing and grazing animals like the ibex may be another contributing factor.144. Immediately adjacent to the timberline, the tundra consists of a fairly plete cover of lowlying shrubs, herbs, and grasses, while higher up the number and diversity of species decrease until there is much bare ground with occasional mosses and lichens and some prostrate cushion plants.145. At this great height, rocks, warmed by the sun, melt small snowdrifts146. This enables them to avoid the worst rigors of high winds and permits them to make use of the higher temperatures immediately adjacent to the ground surface.147. The low growth form can also permit the plants to take advantage of the insulation provided by a winter snow cover.148. The client who pays for the building and defines its function is an important member of the architectural team.149. The mediocre design of many contemporary buildings can be traced to both clients and architects.150. In order for the structure to achieve the size and strength necessary to meet its purpose, architecture employs methods of support that, because they are based on physical laws, have changed little since people first discovered themeven while building materials have changed dramatically.151. Enormous changes in materials and techniques of construction within the last few generations have made it possible to enclose space with much greater ease and speed and with a minimum of material.152. Progress in this area can be measured by the difference in weight between buildings built now and those of parable size built one hundred ago.153. In the past, whole cities grew from the arduous task of cutting and piling stone upon.154. The doorways and windows are made possible by placing over the open spaces thick stone beams that support the weight from above.155. A structural invention had to be made before the physical limitations of stone could be overe and new architectural forms could be created.156. It works in pression to divert the weight above it out to the sides, where the weight is borne by the vertical elements on either side of the arch.157. The doorways and windows are made possible by placing over the open spaces thick stone beams that support the weight from above.158. This region has a semiarid climate, and for 50 years after its settlement, it supported a lowintensity agricultural economy of cattle ranching and wheat farming.159. In the early twentieth century, however, it was discovered that much of the High Plains was underlain by a h