The beliefs of the Warraus have been somewhat modified by contact with foreigners, and perhaps on this account they speak, according to Plassard, of one Supreme Being, the _Gébu_, superior to all the lesser spirits of plenty, famine, fire, and all phenomena of Nature. Earthquakes are looked upon as good signs, indicating the presence of a healthy, invigorating spirit in the earth; a belief not so strange when it is remembered that in the alluvial plains where the Warraus live earthquakes have seldom been sufficiently violent to do harm. The religious rites of the communities are presided over by the _Wicidatu_, like the piache, a mixture of priest and medicine-man. Their worship includes invocations against disease and famine, and prayers for good hunting. To Gébu and the lesser spirits they offer the first-fruits of their harvest, vegetable and animal alike, at the one great festival of the year, for which elaborate preparations are made. All the previous day is spent in preparing provisions, and at dawn on the feast day, their bodies decorated with lines in blue and red, they surround the house of the wicidatu. The priest shortly comes forth, a crown of feathers on his head, and holding a pair of maracas. Shaking these, he leads the crowd to the _rancho_, or hut, set apart for the offerings, and there, sitting on the trunk of a tree, smokes and chants (accompanying himself with the maracas) to Gébu, in whose name he presently takes the offerings. After this he holds a maraca in the air at the length of his arm, shaking it, and after a time bringing it down to his mouth. Then, in a disguised voice, supposed to be that of Gébu, he asks why he is called; in reply the wicidatu salutes and offers the first-fruits, which are accepted. This acceptance is the signal for a general chant of the assembly recounting their petitions, which Gébu, speaking as before through the priest, promises to consider. Finally, the priest alone sings a song of farewell, and Gébu returns to his heaven. The ceremonies over, the wicidatu takes the best of the food and drink, and the remainder provides refreshment during the dancing and revels which occupy the rest of the day. In addition to conducting this public worship the wicidatu acts as doctor in times of sickness, making use of certain simples and invocations to the spirits of the disease. Religious ceremonies are performed round the hut by night, and the medicine-man enters with a cigar of tobacco and herbs and blows the smoke on to the abdomen and chest of the patient. After the fumigation he is left alone for some time, until the wicidatu returns, dances and prostrates himself round the hut, performs the fumigation once more, and finally retires, leaving the sick man to recover or die, according to the manner in which the spirit has been affected by the supplications.