The split between soul and body is, as it were, built into our thinking, and believing in ghost stories comes as easily to us as it did to our ancestors thousands of years ago.

[…]

And yet that current really did pass through me, and truly I, shrunken, hunched over, am still the same instrument—how is that possible?

[…]

Higher–lower. It seems one can hardly accomplish anything without a conviction of one’s own superiority. And one acquires that by looking at the achievements of others through the wrong end of a telescope. Later, it becomes difficult to free oneself from the feeling of the harm one has done.

Czesław Miłosz, Road-side Dog

Over-animal. — The beast within us wants to be deceived; morality is a lie born of necessity, so that we may not be torn apart by that beast. Were it not for the errors hidden in the assumptions of morality, man would have remained an animal. Instead, he began to regard himself as something higher and prescribed harsher laws for himself. Hence his hatred of those degrees that remained closer to animality: this also explains the former contempt for the slave as something non-human, as a thing.

Friedrich Nietzsche, Human, All Too Human

There is at least one reality which we all grasp from within, through intuition and not by analysis alone. It is our own personality in its flow through time. It is our “I,” which endures. We may fail to sympathize intellectually with any other thing. But surely we do sympathize with ourselves.

Henri Bergson, An Introduction to Metaphysics

To live as oneself means: to be a task to oneself. Never say that it is a delight to live as oneself. It will not be joy, but long suffering, for you must become your own creator. If you wish to create yourself, do not begin with the best and the highest, but with the worst and the deepest. Therefore I tell you that to live as yourself awakens disgust within you. — The confluence of the streams of life is not joy, but pain, for it is a violence that imprints itself through violence, guilts that destroy what has been sanctified.

Karl Gustav Jung, The Red Book

The belly of the earth filled with beings. Everywhere there were unfinished creatures crawling over one another like reptiles. It was so crowded there that they trampled one another, spat on one another, and did various indecent things, with the result that louder and louder complaining and lamentation could be heard. In the end, many of them managed to escape from that dark place. They became wiser and more human. (Zuni, United States)

Mineke Schipper, In the Beginning There Was No One

A matter of particular importance to me, which I would like to consider in the context of modernism, is something that might be called the transgression of humanism. It is inevitable that we move away from treating anthropocentrism—that contingent and local form of homeostasis and perception—as the measure of all things. It was a necessary chapter and it bore a few sweet fruits, but it has run its course and it is time to close it. It was pleasant to feel like mommy and daddy’s favorite child, to see oneself as an image made in their likeness, but this illusion can no longer be sustained. Besides, in a certain sense, perhaps it is not an illusion—but to stop there is no longer enough. To say that I am human and that I know all that is human is no longer enough. It is difficult even to accept without qualification that I am, let alone everything else.

At first I have neither beginning nor end; there is nothing more. I have no shape, no weight, no memory. I am all this, and all this is me. But in knowing this I also begin to remember it, and then I begin. I begin to happen. With great momentum I move away from something, I settle into something. I still do not feel my shape clearly, I have no distinct boundaries, but I do have a middle—a center into which I collapse. The longer this lasts, the faster I move away from the beginning and the harder it becomes for me to remember everything that happens. And the more slips away, the more I must let fall into oblivion, the more concrete I become in my limited, ever more distinct form. The less there is in me of all that is—the more there remains outside me than within me—the more it seems to me that I am myself. On the peripheries of memory there remains only an impression of that original wholeness and indivisibility. Not so much a memory of it as a distant, barely audible echo.

So I become myself. I do not remain and I never am; I only become—continually and without end. The continuity of this process, its direction, pace, and presumed goal make up what I call my identity. And this is a paradox. Identity in process is an oxymoron, because identity is incompatible with ceaseless change. Nothing here is identical, only at most similar. I am continually becoming similar to myself. But I am not. Nothing here is at all—there is nothing here. Perception, which gives the impression of access to enduring things, is a convenient illusion, coupled with another impression and another convenient illusion: that I move among these enduring things and that I move them. That I act in this non-existent world. That is how matters stand, and one could place a period here and never say anything more—which is tempting—but I will go on.

I will go on, because stopping there would be a great arrogance. The pseudo-insight of a pseudo-sage, who has glimpsed something through a narrow crack—some little lights and some shadows—and thinks he has understood something of it and is exceptional for that reason. He still eats and shits and rots and dies of fear, yet pretends to himself that tangible reality, reality that happens and hurts, does not concern him, because he has seen through it. So I do not pretend. Or rather, I try not to—I would like to pretend to nothing, and certainly not to a knowledge I have not earned. Nor can I say that I know nothing. That too is a dodge and an escape. I know this and that. I do not become overly attached to the ways in which I am able to express it; I accept that every truth leaks through those ways like water through holes in a bucket. But I do know this and that. Above all, I know that I know what makes me see certain matters in certain ways—ways of which I can have no certainty that they are right—yet some of these matters I must accept as though they were true, taking care not to forget that they are true only as though.

As though:
I know that I become as a body. I awaken as a body, I am conditioned and dependent—as a body. I have bodily weight, I offer resistance, I yield to dynamics. I process something through myself; in fact I am constantly simmering, drawing from something and giving something back. I know that as a body I have boundaries, I have a shape and a structure with certain symmetries and proportions. I know that all of these are dictated by the features of the environment in which my body functions, and that it is one link in a chain of a great many bodies connected with one another more or less directly, all of them deriving from one ancient source. I remember and I plan as a body. I feel as though within my body I were something from outside it, as though I had it at my disposal, resided in it, and wielded it. I feel as though I would one day abandon it and return to something.

But I also know that words, thoughts, and feelings are to an enormous, overwhelming extent empty, like atoms. That their concrete, tangible, localized nature is an illusion. That they join into stories just as atoms join into objects, and that these stories are semblances—though not so much so that one cannot still smash one’s head against them. I know that the boundaries and shapes of my body, though they absolutely condition what and how I am, are fluid—just like the boundaries and shapes of atoms and of the objects built from them, however little this changes my overall condition.

I know that my body (as though it were mine) and its environment are particular, and that I must not go too far in drawing conclusions from them about the general nature of things, even within those categories and systematics in which one may speak of bodies and environments. But I also know that just as a cell is built of atoms, a body of cells, and an environment of atoms, cells, and bodies, so everything is built of environments, and none of them can be so different from the others as not to fit somehow into the whole.

Yes, I know that I am human. And nothing is alien to me.

Some of the maps I have looked into:
Giorgio Agamben, The Open: Man and Animal
Maurice Merleau-Ponty, Phenomenology of Perception
Mads Rosendahl Thomsen, Jacob Wamberg (ed.), The Bloomsbury Handbook of Posthumanism
Stefan Lorenz Sorgner, On Transhumanism
Jakob Johann von Uexküll, A Foray into the Worlds of Animals and Humans