ON THE RELATION OF NATURAL SCIENCE TO ART. 665 
the female for more highly ornamented suitors, a progeny of constantly 
increasing brilliancy of coloring being thus obtained. Male birds of 
Paradise have been observed to vie in showing off their beauty before 
the females during courtship. The power of song in nightingales might 
be attributed to the same cause, the female in this case being more sus- 
ceptible to the charms of melody than to those of brilliant coloring. 
Darwin goes on to observe that, in the human race likewise, certain 
sexual characteristics, such as the imposing beard in man and the lovely 
tresses in woman, might have been acquired through sexual selection.* 
It is a well-known fact that, by repeated introduction of handsome Cir- 
eassian slaves into aristocratic Turkish harems, the original Mongol 
type in many cases has been remarkably ennobled. And carrying the 
same principle further, we may find therein an explanation for the fas- 
cination which female beauty has for man. According to our pres- 
ent views, the first woman was not made of a rib taken out of the first 
man—a process fraught with morphological difficulties. It was man 
himself who, in countless generations, through natural selection, 
fashioned woman to his own liking, and was so fashioned by her. This 
type we call beautiful, but we need only to cast a glance at a Venus by 
Titian, or one by Rubens—let alone the different human races—to recog- 
nize how little absolute this beauty is. 
If one kind of beauty could be said to bear analyzing better than 
another it is what might be termed mechanical beauty. It is noticed 
least, because it escapes all but the practiced eye. This kind of beauty 
may belong to machines or physical apparatus, each part of which is 
exactly fitted to its purpose in size, shape, and position. It answers 
more or less to the definition of ‘unconscious rationality,” our satis- 
faction evidently proceeding from an unconscious perception of the 
right means having been employed to combine solidity, lightness, and, 
if necessary, mobility, with the greatest possible profit in the transmis- 
sion of foree and the smallest waste of material. A driving-belt is 
certainly neither attractive nor unattractive; but it pleases the “ visus 
eruditus” to see a connecting-rod thicken from the ends towards the 
middle, where it has to bear the greatest strain. Of course, this kind 
of beauty is of recent origin. I remember Halske telling me that, as 
regards the construction of physical and astronomical instruments, it 
was, to his knowledge, first understood and established as a principle 
in Germany by Georg von Reichenbach in Munich. Berlin and Munieh 
work-shops produced’ instruments of perfect mechanical beauty at a 
time when those supplied by France and England were still often dis- 
“The author is not unaware of Mr. Wallace’s attack on Darwin’s explanation of the 
brilliant plumage of male birds by the females’ preference, and of the discussion 
arisen between him and Messrs. Poulton, Pocock, and Peckham. This was not the 
proper place to enter into it, the less so as, whatever may be its outcome, the author’s 
conclusion from the theery of sexual selection would remain unaltered. 
