“The acts of living beings are, as a rule, neither all altruism nor all egoism. They consist generally of blends of the two elements, with a preponderance of egoism. It is frequently impossible, too, to estimate just the amount of each element in a given act. An act which may seem altruistic may be in reality only sly and far-sighted egoism.”

It is the extension of the regard which we have for ourselves to those below, above, and around us. It is simply the law of the individual organism widened to apply to the Sentient Organism. It is the message which is destined in time to come to redeem this world from the primal curse of selfishness. It is the dream which has been dreamed by the great teachers of the past independently of each other, merely by observing the actions of men and thinking what rule if followed would cure the wrongs and sufferings of this world.
Source: Ethics and Education (1912), The Larger Self, pp. 58–59

Source: Better-World Philosophy: A Sociological Synthesis (1899), The Preponderance of Egoism, p. 122

Source: Better-World Philosophy: A Sociological Synthesis (1899), Egoism and Altruism, pp. 98–99

Introducing Objectivism. The Objectivist Newsletter, Vol. 1, No. 8. August, 1962. p. 35.

The Law of Mind (1892)

Outline of a Morality Without Obligation or Sanction https://www.marxists.org/archive/guyau/1885/morality.htm (1885).
Context: A third equivalent of duty is borrowed from sensibility and not, like the preceding, from intelligence and activity. It’s the growing fusion of sensibilities, and the ever increasing sociable character of elevated pleasures, from which results a kind of duty or superior necessity which pushes us naturally and rationally towards others. By virtue of evolution, our pleasures grow and become increasingly impersonal; we cannot experience enjoyment within our selves as if on a deserted isle. Our milieu, to which we better adapt ourselves every day, is human society, and we can no more be happy outside of this milieu than we can breathe outside the air. The purely selfish happiness of certain Epicureans is a chimera, an abstraction, an impossibility; the true human pleasures are all more or less social. Pure egoism, rather than being an affirmation of the self, is a mutilation of the self.

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.

Reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 56.

Psychology and Poetry (June 1930)