Another most important consideration is, that male butterflies rival or even excel the most gorgeous male birds in bright colours and elegant patterns; and among these there is literally not one particle of evidence that the female is influenced by colour, or even that she has any power of choice; while there is much direct evidence to the contrary (_Descent of Man_, p. 318). The weakness of the evidence for conscious sexual selection among these insects is so palpable, that Mr. Darwin is obliged to supplement it by the singularly inconclusive argument that, “Unless the female prefer one male to another, the pairing must be left to mere chance, and this does not appear probable” (_l.c._ p. 317). But he has just said--“The males sometimes fight together in rivalry, and many may be seen pursuing or crowding round the same female;” while in the case of the silk-moths,--“the females appear not to evince the least choice in regard to their partners.” Surely the plain inference from all this is, that males fight and struggle for the almost passive female; and that the most vigorous and energetic, the strongest-winged or the most persevering, wins her. How can there be chance in this? Natural selection would here act, as in birds, in perpetuating the strongest and most vigorous males; and as these would usually be the more highly coloured of their race, the same results would be produced as regards the intensification and variation of colour in the one case as in the other. Let us now see how these principles will apply to some of the cases adduced by Mr. Darwin in support of his theory of conscious sexual selection.