“It is not possible, and it never will be possible, to organize all the beings occupying space into one immense confederacy. This would be ideal, but from the inexorable nature of things it can never be. The denizens of the sea depths can not correlate with the inhabitants of the clouds. The lion can not fraternize with the lamb, nor the hawk with the sparrow. The natures of beings have been evolved thru war, and they are in large part irredeemably antagonistic. But the approximation, if honest, may be more successful than is supposed, and may include many species not human. The bird may contribute his song and plumage, the sheep his fleece, the horse, the ox, the elephant, and the camel their strength or speed, the cow and the fowl their secretions, the dog his fidelity, and man his art. The ultimate and ideal aggregation of the living universe will not be a pan-American union nor a Euro-American league, nor even an aggregation whose spirit is embodied in a parliament of man, but the widest and most consummate possible Confederation of the Consciousnesses.”

The Iliad of Homer, Rendered into English Prose (1898), Book XXII

II 12 as translated by Dorothea Waley Singer (1950)
De immenso (1591)

Attributed

Five Essays on Liberty (2002), Historical Inevitability (1954)

Maslow (1954), as cited in: Hiram E. Fitzgerald, ‎Michael G. Walraven (1987). Psychology. p. 119; Also in: Maslow, Toward a Psychology of Being. Simon and Schuster, 1962, p. 5.
Variant quote: Human nature is not nearly as bad as it has been thought to be... It is as if Freud supplied us with the sick half of psychology and we must now fill it out with the healthy half.'
1940s-1960s

We'll Never Conquer Space (1960)
Context: Space can be mapped and crossed and occupied without definable limit; but it can never be conquered. When our race has reached its ultimate achievements, and the stars themselves are scattered no more widely than the seed of Adam, even then we shall still be like ants crawling on the face of the Earth. The ants have covered the world, but have they conquered it — for what do their countless colonies know of it, or of each other?
So it will be with us as we spread out from Earth, loosening the bonds of kinship and understanding, hearing faint and belated rumors at second — or third — or thousandth hand of an ever dwindling fraction of the entire human race. Though the Earth will try to keep in touch with her children, in the end all the efforts of her archivists and historians will be defeated by time and distance, and the sheer bulk of material. For the numbers of distinct human societies or nations, when our race is twice its present age, may be far greater than the total number of all the men who have ever lived up to the present time.
We have left the realm of comprehension in our vain effort to grasp the scale of the universe; so it must ever be, sooner rather than later.

Section IV, p. 12–13
Natural Law; or The Science of Justice (1882), Chapter II. The Science of Justice (Continued)

Cosmic Memory, Prehistory of Earth and Man.