Man has reason, discrimination and free-will such as it is. The brute has no such thing. It is not a free agent, and knows no distinction between virtue and vice, good and evil. Man, being a free agent, knows these distinctions, and when he follows his higher nature, shows himself far superior to the brute, but when he follows his baser nature can show himself lower than the brute.

Self Restraint V. Self-indulgence (ed. 1947)