226 THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



which would probably bring the people to a lower state than ever by 1500 a. d., just before 

 the Spaniards arrived. Since that time a sUght but unimportant recovery might be looked 

 for, but its magnitude would depend on whether om* sequoia curve should he in the upper 

 or lower of the two positions indicated in figure 72. 



Before comparing this inferred history with that which actually occurred, two signals of 

 warning must be set up. In the first place, I would not be understood to imply that climatic 

 changes, with their attendant physiological, pathological, economic, and political results, 

 are the only or main cause of historic events. Doubtless races, like individuals, go through 

 a definite development from youth to maturity and old age. Doubtless such circumstances 

 as luxury, contact with other races, the introduction of new ideas, and the commanding 

 genius of gifted individuals are so important that any one of them may completely reverse 

 the effects of physical environment. Nevertheless, the environment continues to act. 

 An injurious change, like a slow, wasting sickness, may perhaps cause a youthful nation 

 to age prematurely, while a beneficial change, hke the cure of a chronic disease, may 

 restore a youthful buoyancy which had seemed to be forever lost. These things will not 

 change the laws of the rise and decay of nations, nor will they nullify the effect of ideas, 

 inventions, genius, and the thousand other factors which enter into history. The case is 

 exactly hke that of a human being. Nothing can prevent him from passing from youth 

 to maturity and old age; sickness need not necessarily prevent him from enjoying the 

 advantages and stimulus of friendship, reading, and travel; a new interest may temporarily 

 or even permanently overcome a physical weakness that has hitherto prostrated him, 

 and he may die in his youth and strength through accident, or may linger on to extreme 

 old age in spite of chronic illness. Yet all these things do not mean that disease has no 

 effect or that it is not highly important. And so it is with physical environment; favor- 

 able conditions will not make a stupid race brilhant, nor will unfavorable conditions destroy 

 the natural abiUties of a race that is gifted. Nevertheless, changes of climate, like the 

 coming and going of disease, may help or hinder the progress or decline which is taking 

 place as the result of the complex interplay of all the many factors that control historic 

 development. 



Our second warning signal is necessitated by the extreme scantmess of our knowledge of 

 early Maya history. The chief sources of knowledge are, fu'st, certain chronicles which w ere 

 pieced together after the arrival of the Spaniards and were written in the Maya language 

 but with Spanish letters. They pertain only to northern Yucatan and are often confused 

 and inaccurate, but have a distinct historical value. A second but as yet unusable source 

 of knowledge is three or four codices of pre-Spanish date written in Maya hieroglyphics, 

 but the key to their interpretation has not been found and the only intelhgible portion is 

 certain calculations. Many such codices existed at the time of the Spanish conquest, but 

 the conquerors, in their zeal for rehgion, burned all they could lay their hands upon. A 

 third source of knowledge is a considerable number of stelse, lintels, and other monuments, 

 found in connection with temples and bearing dates according to the old Maya calendar. 

 These, unfortunately, are confined to the southwestern portion of Maya land, and only one 

 or two have been found in northern Yucatan. The most important is upon a lintel 

 at Chichen Itza, the greatest city of the region. Finally, our best knowledge of the Mayas 

 is derived from the nature and development of their art and architecture, a subject which 

 has been carefully investigated by Mr. H. J. Spinden, in his recent work, "A Study of 

 Maya Art."* He there sums up the evidence derived from the various sources of knowledge 

 and displays it graphically in a chronological table. Unfortunately, however, the study 

 of art and architecture does not furnish exact dates. Therefore we still remain in great 

 uncertamty as to all but the main outhnes of Maya history, and the statements which 

 follow must be regarded as largely tentative. 



* Memoirs of the Peabody Museum of American Archseology and Ethnology, Harvard University, 1913. 



