developed through the immediate effect of viewing natural phenomena, that much rather the tales preexisted and the explanatory part was tacked on at a later time, precisely as the art forms preexisted and their meaning was tacked on according to the peculiar mental disposition of the individual or the tribe. [73] Oskar Dähnhardt, Natursagen, Vol. 4. Leipzig 1912. The same observation has been made in regard to ceremonials. The so-called sun dance is performed by almost all the tribes of the great plains. The general run of the ceremonial is essentially the same everywhere, although different tribes have added on special characteristic details. The meaning, on the other hand, presents far greater variations. In one case the performance is made in fulfilment of a vow made when supernatural aid is invoked in time of distress; in another case it is undertaken to purchase the right of ownership in a sacred bundle, and then again it is a tribal, seasonal ceremonial.[74] [74] Leslie Spier, Anthropological Papers of the American Museum of Natural History, Vol. XVI, (1921), pp. 457 et seq. These three examples illustrate that the psychological explanation of a custom and its historical development are not by any means the same; on the contrary, owing to secondary interpretations that in course of time set in and the general character of which depends upon the cultural interest of the people, the psychological explanation is much more likely to be quite independent of the actual historical happenings. The mere fact that a tribe explains forms according to a certain pattern does not prove, that they have developed from actual representations of the objects they now represent. It might perhaps be admitted that in the special case of the North American triangle which we have discussed the argument is convincing because no transitional forms exist, that, however, when an almost continuous series of forms is found, beginning with the most realistic and ending with a purely geometrical one, the conclusion cannot be avoided that the development has been in the direction from realism to conventionalism. I have already indicated that as long as there is no historic proof, the sequence might as well be reversed. In all the cases that have been described and that are based on direct inquiry among primitive people regarding the meaning of designs, realistic and conventional forms have been found to occur at the same time. It would therefore be necessary to give a reason why some excellent artists should use the one style, others, equally good ones the other; or why even the same artist should combine the two styles.