The musical tradition of the Pueblo Indians calls for both the performance and the "renewal" of songs. While some of the dance ceremonials do not change from year to year, occasions that call for new songs, and even new dances, are likely to outnumber those for which songs are prescribed. Despite ongoing transformation, there is a continuity of symbolism in the costumes, patterns, words, melodies, instruments, and spirit that make up the dance ceremonials. It is a symbolism durably evolved through centuries alongside dominant Pueblo concerns of farming, hunting, and religious activities. These activities have been traditionally carried on in a fascinating, varied, and arid landscape. The need for sufficient rainfall is a concern of Pueblo inhabitants even today. Pueblo culture has evolved in a way, however, that provides this concern with adequate expression. The dances, for which the songs are made and sung, represent a fulfillment of man's responsibility as a participant in the cosmos. Ancestor spirits demonstrate their appreciation for this observance by coming to attend. They delight in the impersonations of themselves that are performed by the dancers to the accompaniment of new songs. There is great emphasis on the propriety of these dance ceremonials for the ancestor-spirits, or katcina, are understood to visit the village as clouds-clouds that bring rain, rain that brings an abundance of crops and game.