“The chief activities of beings, both human and non-human, are put forth, directly or indirectly, for the purpose of procuring food. The suppression, entire or partial, of one being by another for nutritive purposes is, therefore, the form of the most frequent and excessive egoism. The lowly forms of life—the worms, echinoderms, mollusks, and the like—are, for the most part, vegetarians. So, also, are prevalently the insects, birds, rodents, and ungulates. These creatures are not, as a rule, aggressively harmful to each other, chiefly indifferent. But upon these inoffensive races feed with remorseless maw the reptilia, the insectivora, and the carnivora. These being-eaters cause to the earth-world its bloodiest experiences. It is their nature (established organically by long selection, or, as in the case of man, acquired tentatively) to subsist, not on the kingdom of the plant, the natural and primal storehouse of animal energy, but on the skeletons and sensibilities of their neighbors and friends. The serpent dines on the sparrow and the sparrow ingulfs the gnat; the tiger slays the jungle-fowl and the coyote plunders the lamb; the seal subsists on fish and the ursus maritimus subsists on seal; the ant enslaves the aphidae and man eats and enslaves what can not get away from him. Life riots on life—tooth and talon, beak and paw. It is a sickening contemplation, But life everywhere, in its aspect of activity, is largely made up of the struggle by one being against another for existence—of the effort by one being to circumvent, subjugate, or destroy another, and of the counter effort to reciprocate or escape.”

Source: The Naked Civil Servant (1968), Ch. 16

Variant: Fransisco, what's the most depraved type of human being?

-The man without purpose.
Source: Atlas Shrugged

Encyclical Fides et Ratio, 14 September 1998
Source: www.vatican.va http://www.vatican.va/holy_father/john_paul_ii/encyclicals/documents/hf_jp-ii_enc_14091998_fides-et-ratio_en.html

Criterion Collection essay on Rashamon, excerpted from Something Like an Autobiography as translated by Audie E. Bock (1982) http://www.criterion.com/current/posts/196-akira-kurosawa-on-rashomon
Context: Human beings are unable to be honest with themselves about themselves. They cannot talk about themselves without embellishing. This script portrays such human beings — the kind who cannot survive without lies to make them feel they are better people than they really are. It even shows this sinful need for flattering falsehood going beyond the grave — even the character who dies cannot give up his lies when he speaks to the living through a medium. Egoism is a sin the human being carries with him from birth; it is the most difficult to redeem. This film is like a strange picture scroll that is unrolled and displayed by the ego. You say that you can’t understand this script at all, but that is because the human heart itself is impossible to understand. If you focus on the impossibility of truly understanding human psychology and read the script one more time, I think you will grasp the point of it.

Quoted in the documentary The Question Mark Inside broadcast in the UK by Sky Arts (30 October 2009).

An Address on Abraham Lincoln before the Republican Club of New York City (12 February 1909) http://web.archive.org/20050322051431/www.historycooperative.org/btw/Vol.10/html/35.html
Context: Of all forms of slavery there is none that is so harmful and degrading as that form of slavery which tempts one human being to hate another by reason of his race or color. One man cannot hold another man down in the ditch without remaining down in the ditch with him.

19th World Vegetarian Congress 1967

The Political Economy of Media: Enduring Issues, Emerging Dilemmas by Robert W. McChesney ISBN 978-1-58367-161-0.