“Lights and shadows are continually flitting across my inward sky, and I know neither whence they come nor whither they go; nor do I inquire too closely into them,” Nathaniel Hawthorne wrote in his notebook one spring day in 1840. “It is dangerous to look too minutely into such phenomena. It is apt to create a substance where at first there was a mere shadow… It is best not to strive to interpret it in earthly language, but wait for the soul to make itself understood.”

A century after him, the French philosopher Simone Weil — another visionary of uncommon insight into the depths of the soul — contemplated the paradox of friendship, observing that “it is a fault to wish to be understood before we have made ourselves clear to ourselves.”

For one consciousness to understand another — to understand what it is like to be another — might be the supreme challenge of communication and coexistence, because we each move through life half-opaque to ourselves. We aim the analytical mind — that magnificent novelty-instrument millennia in the evolutionary making — at the opacity, but occluding the lens of self-understanding is something much more primeval: Emotion smudges the eyepiece of life, often without our awareness, changing what we see and making us react not to what is but to what we are perceiving. Anyone with moderate self-awareness can relate to the experience of having an irritable or indignant or melancholy mood descend upon them seemingly out of the blue, when it has in fact coalesced out of an invisible and pervasive atmosphere of unprocessed feeling: Who among us has not, in a human moment, aimed a flash of fury at the wrong person for the wrong thing because something entirely else is filling the sky of the mind with its charged nimbus of wrongness.

Why emotion so easily clouds the lens of experience is what psychiatrist trio Thomas Lewis, Fari Amini, and Richard Lannon explore throughout A General Theory of Love (public library) — the altogether revelatory book that remains, in my life of reading, the single most illuminating inquiry into the neurological nature and psychological nurture of why we feel what we feel and how this shapes how we become what we are.

Drawing an analogy to music — which might be so elemental to our sense of aliveness precisely because it shares a fundamental neuropsychological mechanism with emotion — Lewis, Amini, and Lannon examine the composition of feeling out of neural notation, illuminating the interdependence of and difference between emotion and mood:

Emotions possess the evanescence of a musical note. When a pianist strikes a key, a hammer collides with the matching string inside his instrument and sets it to vibrating at its characteristic frequency. As amplitude of vibration declines, the sound falls off and dies away. Emotions operate in an analogous way: an event touches a responsive key, an internal feeling-tone is sounded, and it soon dwindles into silence. (The figures of speech “pluck at one’s heartstrings” and “strikes a chord in me” have found a home in our language for just this reason.) Rising activity in the emotion circuits produces not sound, but (among other things) a facial expression. When the neural excitation exceeds a shadowy threshold of awareness, what emerges is a feeling — the conscious experience of emotional activation. As neural activity diminishes, feeling intensity decreases, but some residual activity persists in those circuits after a feeling is no longer perceptible. Like the ghost of Hamlet’s father, an emotion appears suddenly in the drama of our lives to nudge the players in the proper direction, and then dissolves into nothingness, leaving behind a vague impression of its former presence.

Against this haunted backdrop of feeling, the dance of mood plays out, twirling us into tumult with its persuasive percussion:

Moods exist because of the musical aspect of an emotion’s neural activity, the lower portion imperceptible to our conscious ears… A mood is a state of enhanced readiness to experience a certain emotion. Where an emotion is a single note, clearly struck, hanging for a moment in the still air, a mood is the extended, nearly inaudible echo that follows. Consciousness registers a fading level of activation in the emotion circuits faintly or not at all. And so the provocative events of the day may leave us with emotional responsiveness waiting beneath our notice… Since the neural activation that creates a given emotion decreases gradually, provoking it again is easier within the window of the mood.

By these imperceptible pulsations and resonances, our present experience comes to reverberate with echoes of the past:

A musical tone makes physical objects vibrate at its frequency, the phenomenon of sympathetic reverberation. A soprano breaks a wineglass with the right note as she makes unbending glass quiver along with her voice. Emotional tones in the brain establish a living harmony with the past in a similar way. The brain is not composed of string, and there are no oscillating fibers within the cranium. But in the nervous system, information echoes down the filaments that join harmonious neural networks. When an emotional chord is struck, it stirs to life past memories of the same feeling.

[…]

A particular emotion revives all memories of its prior instantiations. Every feeling (after the first) is a multilayered experience, only partly reflecting the present, sensory world.

Over the sweep of time, our lived experience thus rewires the brain, generating a forceful momentum of emotional habit. What we have felt comes to shape what we most easily and readily feel, unstringing the harp of reality. We come to perceive the world not as it is but as we are. At the heart of this reality-discord are what Lewis, Amini, and Lannon term Limbic Attractors — pre-conditioned patterns of interpretation of incoming sensory data, densely networked and deeply ingrained in the limbic brain, activated so reflexively and powerfully that they can obscure and overwhelm the raw signal of reality.

Limbic Attractors are the source of the blindness that makes us so opaque to ourselves, but they are also a portal to transcending our own limitations by linking up to other minds, sympathetic and sonorous with different feeling-tones. Through such mutual harmonics — nowhere more powerful than in the limbic linkage we call love — we can recompose our own patterned soundtrack of emotion:

Because human beings remember with neurons, we are disposed to see more of what we have already seen, hear anew what we have heard most often, think just what we have always thought. Our minds are burdened by an informational inertia whose headlong course is not easy to slow… No individual can think his way around his own Attractors, since they are embedded in the structure of thought… Because limbic resonance and regulation join human minds together in a continuous exchange of influential signals, every brain is part of a local network that shares information — including Attractors.

[…]

Through the limbic transmission of an Attractor’s influence, one person can lure others into his emotional virtuality. All of us, when we engage in relatedness, fall under the gravitational influence of another’s emotional world, at the same time that we are bending his emotional mind with ours. Each relationship is a binary star, a burning flux of exchanged force fields, the deep and ancient influences emanating and felt, felt and emanating.

In any such binary star system, this limbic resonance allows two people to harmonize their Attractors, fine-tuning the respective musical tones that most easily flow from each consciousness — Pythagoras’s music of the spheres and Kepler’s celestial harmonics, right here on Earth, in the infinite universe of the human heart:

In a relationship, one mind revises another; one heart changes its partner. This astounding legacy of our combined status as mammals and neural beings is limbic revision: the power to remodel the emotional parts of the people we love, as our Attractors activate certain limbic pathways, and the brain’s inexorable memory mechanism reinforces them. Who we are and who we become depends, in part, on whom we love.

Complement this fragment of the altogether illuminating A General Theory of Love with poet Ronald Johnson on matter, music, and the mind, then revisit José Ortega y Gasset on how our loves shape our character and George Saunders on breaking our patterns to unbreak our hearts.