The consequence was that, whenever there was a holiday and the
school was shut, Heatherley employed the time in mending the
skeleton; Butler's picture represents him so engaged in a corner of
the studio. In this way he got his model for nothing. Sometimes he
hung up a looking-glass near one of his windows and painted his own
portrait. Many of these he painted out, but after his death we
found a little store of them in his rooms, some of the early ones
very curious. Of the best of them one is now at Canterbury, New
Zealand, one at St. John's College, Cambridge, and one at the
Schools, Shrewsbury.

This is Butler's own account of himself, taken from a letter to Sir
Julius von Haast; although written in 1865 it is true of his mode of
life for many years:

I have been taking lessons in painting ever since I arrived, I
was always very fond of it and mean to stick to it; it suits me
and I am not without hopes that I shall do well at it. I live
almost the life of a recluse, seeing very few people and going
nowhere that I can help--I mean in the way of parties and so
forth; if my friends had their way they would fritter away my
time without any remorse; but I made a regular stand against it
from the beginning and so, having my time pretty much in my own
hands, work hard; I find, as I am sure you must find, that it is
next to impossible to combine what is commonly called society and
work.

But the time saved from society was not all devoted to painting. He
modified his letter to the Press about "Darwin among the Machines"
and, so modified, it appeared in 1865 as "The Mechanical Creation"