been useless and injurious to the success of the book to have
paraded, without giving any evidence, my conviction with respect
to his origin.

But when I found that many naturalists fully accepted the
doctrine of the evolution of species, it seemed to me advisable
to work up such notes as I possessed, and to publish a special
treatise on the origin of man. I was the more glad to do so, as
it gave me an opportunity of fully discussing sexual selection--a
subject which had always greatly interested me. This subject,
and that of the variation of our domestic productions, together
with the causes and laws of variation, inheritance, and the
intercrossing of plants, are the sole subjects which I have been
able to write about in full, so as to use all the materials which
I have collected. The 'Descent of Man' took me three years to
write, but then as usual some of this time was lost by ill
health, and some was consumed by preparing new editions and other
minor works. A second and largely corrected edition of the
'Descent' appeared in 1874.

My book on the 'Expression of the Emotions in Men and Animals'
was published in the autumn of 1872. I had intended to give only
a chapter on the subject in the 'Descent of Man,' but as soon as
I began to put my notes together, I saw that it would require a
separate treatise.

My first child was born on December 27th, 1839, and I at once
commenced to make notes on the first dawn of the various
expressions which he exhibited, for I felt convinced, even at
this early period, that the most complex and fine shades of