My dear Wallace

Bates was quite right, you are the man to apply to in a difficulty. I never heard any thing more ingenious than your suggestion & I hope you may be able to prove it true.¹ That is a splendid fact about the white moths: it warms one’s very blood to see a theory thus almost proved to be true.² With respect to the beauty of male butterflies, I must as yet think that it is due to sexual selection; there is some evidence that Dragon-flies are attracted by bright colours; but what leads me to the above belief is, so many male Orthoptera & Cicadas having musical instruments. This being the case the analogy of birds makes me believe in sexual selection with respect to colour in insects.³ I wish I had strength & time to make some of the experiments suggested by you;⁴ but I thought butterflies w^d not pair in confinement; I am sure I have heard of some such difficulty.

Many years ago I had a dragon-fly painted with gorgeous colours but I never had an opportunity of fairly trying it.

The reason of my being so much interested just at present about sexual selection is that I have almost resolved to publish a little essay on the Origin of Mankind, & I still strongly think (tho’ I failed to convince you, & this to me is the heaviest blow possible) that sexual selection has been the main agent in forming the races of Man.⁵

By the way there is another subject which I shall introduce in my essay, viz expression of countenance; now do you happen to know by any odd chance a very good-natured & acute observer in the Malay Arch. who you think w^d make a few easy observations for me on the expression of the Malays when excited by various emotions? For in this case I w^d send to such person a list of queries.⁶

I thank you for your most interesting letter & remain | yours very sincerely | Ch. Darwin