On the "Expression of Emotion in Man and Animals" (1872).

"Fertilization of Orchids" (1862), "The Effects of Cross and
Self-Fertilization" (1876), and "The Formation of Vegetable Mould
through the Action of Worms" (1881).

Ill-health, death, and burial.

Personality, tastes, and mental characteristics.

His beliefs and agnostic attitude toward religion.

His prime postulate, that species have been modified during a long
course of descent.

Antagonistic views on the immutability of species.

His theory of natural selection: that all animal and plant life has a
common progenitor, difference in their forms arising primarily from
beneficial variations.

Enunciates in the "Descent of Man" the great principle of Evolution, and
the common kinship of man and the lower animals.

Biological evidence to sustain this view.

Man's moral qualities, and the social instinct of animals.

Religious beliefs not innate, nor instinctive.