Hundreds of examples of these primitive religious chants have been collected of recent years, when, for the first time, their ethnologic importance has been understood. They present a striking similarity, whether from the Polynesian Islands, the desert-dwellers of Australia, or the Navahoes and Sioux of our own reservations. Many of them are scarcely more than inarticulate cries, but even these have a certain likeness, containing the same class of vowels, and often leading, through this physiological correlation of sound to emotion, to similar words in the religious language of far-distant peoples. Everywhere we find these metrical outbursts controlled by the sense of rhythmical repetition; and it was to accentuate this that instruments of music were first invented. Their rudest forms may be seen in the two flat sticks which the Australians use to beat time for their singing in their _corroborees_, or festal ceremonies; or in the hollow log, pounded by a club, which some Central American tribes still employ. All the native American musical instruments appear to have been first invented for aiding the ritual; and tradition assigns with probability the same origin for most of those in the Old World. Uniform rhythmic motion is a powerful means of intensifying collective suggestion; and its action is the more potent the more we yield our minds to the control of their unconscious activities,—the realm in which the religious sentiment is supreme. In the initiation ceremonies of the Australians—called the _Bora_—the youth are obliged to listen to long speeches from the old men, containing instructions in conduct and the ancestral religious beliefs. Such customs as this,—and in one or another form they are universal in primitive religions—led to the development of the art of Oratory. It was cultivated assiduously in primitive conditions. We have several volumes largely filled with the prolix addresses of the Aztec priests and priestesses on various solemn occasions, as birth, entering adult life, marriage, etc.[290] To learn these long formulas by heart was one of the duties, and not an easy one, of the neophytes. In most tribes they are couched in forms apart from those of daily use, the words being unusual, with full vowels and sonorous terminations. Some of these peculiarities survive in the “pulpit eloquence” of our own day, testifying to the influence of religious thought on the development of the modes of dignified expression.