Specifically, in writing of Adam's "longing for communion" that is fulfilled in Eve, he points out that "It is just such a longing, and not the expansion of the creature's cranial cavity, that constitutes the precondition for the other-directed self-sacrifice which uniquely distinguishes our species."
I didn't put it quite that way, but I have many times emphasized that humanness cannot be the result merely of bigger brains, irrespective of how big. Rather, unless selves are intersubjective, then there can be no selves at all. Bigger brains are a necessary condition, to be sure, but not a sufficient one.
The two most important extra-genetic sufficient conditions are 1) being born premature and neurologically incomplete, and 2) maternal empathy, the latter of which is a "feeling with" the personhood of the baby.
Here we go, into another aside. Can't be helped. I'll try to make it brief. For my money, Bion provides the most fruitful way of looking at this.
Biological evolution has been going on for what, 4.5 billion years? Yet despite all that has happened since then, they say the most consequential development of all occurred with the emergence of eukaryotes some 2 billion years ago, give or take. The details aren't important, the main point being that -- to the best of my recollection -- one type of cell learned to survive by living inside another type, and voila! The rest is (evolutionary) history, "since eukaryotes include all complex cells and almost all multicellular organisms," up to and including us.
The point I want to make is that -- so to speak -- it was not good that prokaryotes should be all alone. Rather, had that been the case, then evolution would have been stymied. The details of exactly how it occurred don't really matter, for the principle is the same: life "entered" life and become something much more complex.
Well, the same principle applies to persons. Just as there was a sharp limit to how far prokaryotes could evolve, so too is there a limit on how far isolated, individual minds could evolve. Rather, we had to somehow become members of one another, i.e., intersubjective.
The hinge of all this is again the helpless and neurologically incomplete infant who must evoke the mothering necessary for it to survive, or this little evolutionary experiment is over in one generation.
I'm just going to summarize, but for Bion, it is as if the mother's job is to "think" the thoughts of the infant before the infant is capable of doing so. This may sound odd unless you've had a child, in which case it will sound about right.
Indeed, in the past I've written of how my wife used a particular technique with our preverbal baby, of putting his thoughts and emotions into words, such as "Tristan is angry!" or "Tristan doesn't want to leave the park!" This always had the effect of calming him and making him quite reasonable. Believe it or not, he's been reasonable ever since. And he's remarkably articulate with regard to his inner life -- much more so than I was until, I don't know, around age 40 or so.
Bion calls the thoughts without a thinker beta elements. The mother's job is to process the beta elements through what he calls alpha function. This is what one does with babies, and it also happens to be what one does with patients in psychotherapy -- that is to say, one tries to help the patient articulate unconscious experience.
Assuming we have been successfully mothered (and I use that term in the generic sense to stand for the whole environment of the developing child), then we internalize alpha function and become capable of thinking our own thoughts and metabolizing our own experience.
But the ultimate point is that thinking is an internalized relationship. And any number of pathologies result from degrees of failure to internalize alpha function. Then, instead of thinking thoughts, the thoughts become symptoms, manifesting in the body (somatization), or moods and anxieties, or interpersonal conflicts, or acting out, or substance abuse, or political pathologies, etc.
End of aside. Just note that the development of alpha function is analogous to the emergence of eukaryotes, only in a higher key. Not a coincidence. Just God punning again.
Consider what Bailie says about Eve being made from Adam's rib, which "is typically symbolized in our time by the heart, especially if we see the heart, not as the seat of emotions and even less the source of sentimentality, but -- as the ancients did -- as the source of a wisdom and understanding greater than that arising from cogitation alone" (emphasis mine).
Note the familiar pattern: something from one is internalized by the other, making for a more complex entity. "God took the heart out of the man and put it into the woman," for which reason Adam exclaims "This at last is bone of my bone and flesh of my flesh!" And perhaps even more to the point, "psyche of my psyche," or "being of -- or with -- my being," AKA intersubjectivity. The one is literally inside the other.
Here we have the remarkable moment "when love appeared in the world for the first time..." Or was it? In my book I emphasized the irreducibly trinitarian nature of it all, in that the helpless infant evokes the mother it requires to survive, as mother evokes the husband she and the baby need to survive. In short, the tripartite family becomes the "unit" of civilization.
Bailie often speaks of "things hidden since the foundation of the world," in reference to human sacrifice. Well, this is another one of those things, only hidden in plain sight. I was reminded of it by a link at Happy Acres that goes to the idea that the ones we love are more a part of us than our own parts.
In other words, I could lose a leg, or a kidney, or an eye, and still be me. But remove my son, and that would be infinitely worse than mere amputation. The father expresses it well: "he knows me better than anyone, and that's how I like it." Note the orthoparadox here: for alpha function isn't actually a one-way street. Rather, through our relationship with our children, we become aware of parts of ourselves that would otherwise be unconscious and un-actualized.
Bailie quotes Ratzinger, who writes of "letting ourselves be torn away from the selfishness of someone who is living only for himself and entering into the great basic orientation of existing for the sake of another."
bottom penultimate line is that although "prehuman men," for lack of a better term, were "in possession of all the neurological wherewithal requisite to human experience, the full actualization of his humanity awaited the moment when he came out of himself and discovered the mystery that was his true calling: self-sacrificial love" (Bailie).
However, "there is no reason to doubt that the more typical situation in which the bonding event occurs is the moment of exchange of loving gazes between a mother and a child" (ibid.).
So there you are. We'll have to agree to agree.
We cannot say that they love with each other until the two love a third in harmonious unity, lovingly embracing him in common, and the affection of the two surges forth as one in the flame of love for the third. --Richard of Saint Victor, in Bailie