Although Bloom's entire dialogue with his cat probably reflects its influence, two sentences in particular allude to a section of Michel de Montaigne's Apology for Raymond Sebond (1568). Bloom thinks, "They call them stupid. They understand what we say better than we understand them." These sentences acknowledge Montaigne's conviction that human intelligence and language are not so extraordinary as human beings commonly suppose: their origins lie in animal powers, and many analogues to their operations can be found in other creatures.
Montaigne's Apology is a sprawling examination of various Christian theological positions, relentlessly critical of the vanity of human presumption and animated throughout by skepticism about the efficacy of human reason. In one highly readable section this skepticism takes the form of comparing the mental powers of human beings to those of animals. Early in that section Montaigne writes of man, "How does he know, by the force of his intelligence, the secret internal stirrings of animals? By what comparison between them and us does he infer the stupidity that he attributes to them? / When I play with my cat, who knows if I am not a pastime to her more than she is to me?" (trans. Donald Frame).
When Joyce substituted "undertand what we say" for "play with," he was borrowing from another passage a few sentences later in the Apology: "This defect that hinders communication between them and us, why is it not just as much ours as theirs? It is a matter of guesswork whose fault it is that we do not understand one another; for we do not understand them any more than they do us." Here and elsewhere in the essay Montaigne argues that animals understand the intentions of other animals, albeit imperfectly, through various kinds of signals, often across species boundaries. Horses can tell when a dog's bark expresses aggression toward them; hearing another kind of bark, they are not alarmed. Birds utter different cries for different situations and their meaning is understood, often by other species. Nor are sounds needed to signify: countless physical gestures can communicate intentions, in animals as in humans.
In addition to the many varieties of language, and the many structures, both social and architectural, that animals build, Montaigne argues that their behaviors show clear evidence of intellectual processes, to any observer who is not stubbornly determined to dismiss them as unconscious products of natural instinct. The fox that decides where to cross a frozen river by putting its ear to the ice to listen for rushing water; the dog that follows its master to three branching paths and, after finding no scent on two of them, goes charging up the third without sniffing; the thirsty bird that drops stones into a container until the water at the bottom rises to the top: in these and dozens of other examples Montaigne infers that the animal is thinking, just as everyone would infer that a human being who behaved similarly was thinking. He also observes evidence of compassion, fidelity, cooperation, gratitude, shame, anger, trickery, playacting, and a host of other supposedly human emotions, virtues, and powers.
Bloom converses with his cat, and he attributes not only understanding but also humanlike emotions to her: "vindictive," "cruel." The narrative hovering near his consciousness does the same thing: "shameclosing eyes," "mewing plaintively," "dark eyeslits narrowing with greed." Later in Calypso the transference is reversed: "The ferreteyed porkbutcher," "foxeyes," "They used to believe you could be changed into an animal." To some extent Bloom is undoubtedly anthropomorphizing his cat, and the transformations of people into animals are more fanciful than declarative. But all these meditations on the commonalities between human beings and animals introduce the notion that the different species exist on a biological and psychological continuum.
In previous chapters Stephen has imagined himself as a "dogsbody" and viewed a dog on the beach in strikingly human terms. Bloom's interest in animals breeds an interest in vegetarianism, and also a sense of compassion: he feeds not only his cat but also gulls hovering over the Liffey and a dog roaming the streets of Nighttown, and he once took a homeless dog into his household. He would probably agree with Montaigne that "those who keep animals should be said rather to serve them than to be served by them."
Ulysses in general might be said to exemplify Montaigne's statement that "We are neither above nor below the rest." Humanity is part of an interconnected web of living things, and indeed things in general. The novel adumbrates a post-humanist perspective that might properly be called ecological.