390 



NA TURE 



[February 21, 190T 



there is but one step between the impromptu dance 

 or poem which tells of a recent occurrence and 

 the work of art which transmits the memory of that 

 occurrence to posterity, yet it appears that there are 

 savages who have no historical art. On the other hand, 

 the historical art has everywhere reached its highest state 

 of development amongst nations who have had to hold 

 their own against neighbouring tribes. 



Before discussing the problems of art and sexual selec- 

 tion, of the origin of self-decoration and of erotic art, 

 the author devotes a chapter to a consideration of animal 

 display, and his treatment of the subject is worthy of the 

 attention of zoologists. He arrives at the conclusion that 

 human sexual selection did not create any quality of 

 beauty and that human decoration, like that of animals, 

 is mainly an advertisement of likeness of kind ; but, 

 strange as it may appear, scarcely any form of dress or 

 ornament can be quoted which could be considered with 

 certainty an outcome of the impulse to attract or charm 

 the opposite sex. Decorations of various kinds are con- 

 ferred on young people on attaining puberty, and indicate 

 a new social status, and various subsequent advances in 

 rank have their appropriate decoration. The impulse to 

 ostentation with regard to rank, valour or wealth is un- 

 ' deniably independent of sexual selection. Even where 

 there is no competition between rivals, sexual emotions 

 may still find an artistic expression. Like the courting 

 display of many birds, men may have resorted to song 

 and dance as a mode of overcoming the instinctive coy- 

 ness of the female after sexual selection has operated ; 

 but the strong emotional tension of such periods must in 

 any case seek relief by sound or movement. 



It is evident that a pantomimic imitation of any ac- 

 tivity must, as exercise and stimulation, facilitate the 

 subsequent real execution of the same activity. Indi- 

 viduals and nations who have grown familiar in play with 

 the most important actions in life's work have thus 

 acquired an unquestionable advantage in the struggle for 

 existence. This holds good alike for the everyday occupa- 

 tions of life as for war. Music and song have especially 

 been useful stimuli to work, partly to overcome natural 

 laziness or inertia, partly to efifect unison in the actions of 

 several workers ; for instance, the regularity of the action 

 of many peoples is explicable as a result of the rhythm- 

 ical songs by which their work is accompanied. This 

 applies with equal force to war ; hence it is not surprising 

 to find highly developed choral dances in those peoples 

 in whose life war is a customary occurrence. The need 

 of stimulation is never so great as when a man has to 

 risk his life in an open battle, and with this end in view 

 the military singers of some tribes are able to work 

 themselves and their audience up to a pitch of frenzy 

 which is almost equal to that produced by the dances. 

 Courage is also induced by the effort to appear formid- 

 able and courageous. Instruction in grimacing even 

 formed a part of the military education of the Maoris. 

 Hence, too, the frightful decorations which so many peoples 

 employ when going on the warpath and the well-known 

 face-shields of some of the tribes of New Guinea and 

 Borneo. The decorative art of warlike peoples is usually 

 characterised by a vigour and originality which dominate 

 also their poetry and dramatic dances, and which are 

 NO. 1634, VOL. 63] 



the outcome of an intense and forcible life ; but descrip- 

 tive and figurative art, in the sense of realistic, faithful 

 rendering of nature and life, has never attained any high 

 development among the most military tribes. 



Sympathetic magic which is based upon a likeness 

 between things calls forth imitations of nature and life 

 which, although essentially non-aesthetic in their inten- 

 tion, may nevertheless be of importance for the historical 

 evolution of art. Nor is this confined to the primitive 

 or decorative arts. There are many magical dances and 

 pantomimes, and there is an universal belief in the 

 efficacy of incantations and in magical songs and poems. 



Every man seeks automatically to heighten his feel- 

 ings of pleasure and to relieve his feelings of pain. The 

 artist is the man who finds that he can gain such enhance- 

 ment or relief, not only by the direct action of giving 

 expression to his feeling, but also by arousing a kindred 

 feeling in others. Hence originates in him that desire 

 to transmit his moods to an external audience, and there 

 also arises the endeavour to give the artistic product a 

 form which may facilitate the revival of the original 

 state in an ever-widening circle of sympathisers. 



" Beyond the fact that art has been obliged to avail 

 itself of media which have originally been called into 

 existence by utilitarian, non-a;sthetic needs, there lies 

 another fact. To these external ' origins ' we can also 

 trace some of the most important qualities which we 

 appreciate in a work of art. In this way it is open to 

 us to explain how several of the virtues of art, as we 

 know it, may be derived from the primitive needs which 

 it subserved ; how, for instance, the lucidity of art may 

 find its explanation in art's use for conveying information ; 

 how the sensuous and attractive qualities of all art may 

 be traced to the need for propitiating favour ; how the 

 power that resides in art to trace and stimulate the mind 

 may be transmitted from the days when the artist 

 was appointed to nerve his fellows for work or war. And, 

 lastly, it might be argued that a most characteristic 

 quality of art — the imagination — which is in a sense 

 faith in the reality of the unreal, may have been im- 

 mensely heightened by the use of art for purposes of 

 magic, which fuses the visible and the invisible." 



Alfred C. Haddon. 



THE PARTIAL DIFFERENTIAL EQUATIONS 

 OF MODERN MATHEMATICAL PHYSICS. 



Die Partiellen Differentialgleichtingen der niathema- 

 tischen Physik. Nach Riemawis Vorlesuni^en. Fourth 

 edition. Revised and rewritten by Heinrich Weber. 

 Vol. i. Pp. xvii -1- 506. (Brunswick: Friedrich Vieweg 

 und Sohn, 1900.) 



THE lectures, delivered at the University of G6ttingen 

 by Prof. Bernard Riemann in the sessions of 

 1854-55, of 1860-61 and in the summer of 1862, have, 

 thanks to the volume brought out after Riemann's death 

 under the editorship of Karl Hattendorff, long ranked 

 among the mathematical classics. The third and 

 last edition of " Partielle Differentialgleichungen" ap- 

 peared in 1882, and two years ago Prof. Heinrich Weber 

 was entrusted with the task of bringing out a fourth 



