Although I suspect the idea was circulating around the entire ancient world, in and outside of what we call Greece today, it was Plato who codified the basic idea of humanism, in his dialogue the Theaetetus, in a simple formulation that goes, Man is the measure of all things. The line––the notion––generated a history that we're still saddled with today, chained or tethered to, despite the fact that it's served the planet miserably, but also women, people of color, and animals, among others.
It's a bit odd to insist that Homer, reciting stories several centuries before Plato was even born, might be a post-humanist avant la lettre, though it makes sense in a backward reading, that is in a world in which humanism still has us in an iron grip. Timothy Morton points out in HumanKind that the rise of agrarian culture ten thousand years ago got the humanist ball rolling. It caused in human animals a sense of mastery over the landscape, seasons, time, and nonhumans. The construction of walls, cities, heredity, paternity, and matrimony only enshrined the idea that humans are special, which is to say better, or so the reasoning goes.
Homer begged to differ. On the one hand he affirmed the value of bare life generally, which is apparent in Book XI of the Odyssey when the wanderer travels to the underworld and meets Achilles. He flatters the great warrior, assuring him that everybody above ground celebrates him as the greatest, as do those there below. But Achilles wants none of it. He remarks, "Let me hear no small talk . . . from you, Odysseus. . . . Better, I say, to break sod as a farm hand for some poor country man, on iron rations, than lord it over all the exhausted dead" (ll. 577-81). It's an uncanny affirmation of life in any existential condition, even as it references the agricultural dominance of humans over the land.
If the basic message in the underworld scene is a version of carpe diem, the idea that being alive is always preferable to being dead, the poet complicates the dynamics of what it means to be alive, who matters and who doesn't, in Book XVII. By that point in the epic the missing king has already returned home. He's revealed himself to his swineherd, Eumaios, who failed to recognize him by his own lights, and exacted a promise that he'll keep his identity secret in an effort to take the suitors by surprise. The only character to recognize the hero-in-rags, unaided, is his dog, Argos.
He constitutes a character in his own right, one who suffers because of the general––the humanist––mistreatment of nonhuman animals. Homer makes a point of dramatizing the condition of the dog at the hands of the dim-witted antagonists, the suitors. The narrator laments, "Treated as rubbish now, he lay at last upon a mass of dung before the gates––manure of mules and cows, piled there until fieldhands could spread it on the king's estate. Abandoned there, and half destroyed by flies, old Argos lay" (ll. 83-89).
On one level, Argos mirrors the great hero, who again is outfitted in rags when he first witnesses his canine friend––the state of mutual unrecognizability and what it implies is mirrored in the very pairing Odysseus/Argos. But the poet makes a specific point of Argos' intelligence as well, bespeaking a discernment, loyalty, long-suffering, patience, and outright love––the very traits the suitors lack, thereby reversing the usual hierarchy, casting Argos as human and the suitors as animals. In that way Homer turns what will become the humanist tradition on its ears. In a moving passage full of pathos the narrator remarks, "When he knew he heard Odysseus' voice nearby, [Argos] did his best to wag his tail, nose down, with flattened ears, having no strength to move nearer his master. And the man looked away, wiping a salt tear from his cheek . . . . Then he said, 'I marvel that they leave this hound to lie here on the dung pile . . . .'" (ll. 389-97). The two speak to each other, albeit in different modes, one via words and the other gesture, a mutually-discernible language.
Remembering that the epic is not just a story but a great work of poetry, it's important not to overlook the metaphorical heft of the motif of an animal reduced to a dung pile, which is precisely where the humanist tradition places him. Odysseus' lamentation, the shedding of tears over the sorry state of animal affairs, underscores the point. The image is all the more poignant when we keep reminding ourselves that Argos has accomplished something no human character manages to pull off. Eumaios and Telemachos must be told in two epiphanic scenes that the hero has returned. Odysseus' old maid, Eurycleia, recognizes him only with the tip-off of the scar. And even the hero's wife, Penelope, only liminally understands, Oh! That's him! though not consciously. Argos on the other hand, gets it. Upon merely hearing the returned king's voice, he "pricked up his ears" (ll. 375). Argos discerns what no human can.
As Jacques Derrida reminds us in The Animal That Therefore I Am, the humanist tradition, from Plato and Aristotle up through Descartes and until today––the entire Western philosophical tradition––would go on to sanction deplorable treatments toward nonhuman animals by human animals. The anthropocentric tradition allowed the creation of a pet exception, which afforded special status for cats, dogs, and a handful of other animals while treating domestic and "wild" animals like products to be exploited, commodities, cast as incapable of suffering––eighty billion animals are slaughtered globally each year today, after enduring execrable conditions.
It's possible Homer was also guilty of the pet exception. But given his widespread
use of allegory in the work, it's more likely that Argos represents all nonhuman creatures, and Odysseus' tears signal a way of viewing their ongoing mistreatment. Since the dawn of human agriculture we've reduced nonhuman beings largely to a kind of shit pile. Homer gives us a lens through which to view not just the limits but the immorality of our behavior, and the humanist tradition generally.
(Quotes from Homer, The Odyssey. Trans. Robert Fitzgerald. NY: FSG, 1999)