Once, in an extreme of despair, I posed to my therapist a version of the haunting thought experiment Mary’s Room: How, I asked her, can a person who has never been modeled healthy, secure, steadfast love even recognize it when it comes along — to what extent is this knowing teachable, learnable? If a person has never seen the color blue, never experienced blueness in their creaturely sensorium, there are certain things you can do to convey to them a knowledge of it — give them the electromagnetic wavelength of the color and examples of blue things and a conceptual portrait of what blue feels like — but all they will ever do is run around the world with this checklist of criteria in hand, asking: “Is this blue? How about this?”

She paused for a moment, then said: “Maybe they will never see blue the way you or I see it, but they can have an experience that is entirely new and entirely wonderful — and that will be their blue.”

In 1672, holding up his finger in the shadow between the light from his candle and the rising sun, the German polymath Otto von Guericke was astounded to see his flesh turn an “azure blue of the utmost beauty.” Shadow, produced by the absence of light and therefore the absence of color we call black, suddenly had a hue — an optical effect caused by the contrast between different light sources.

Strolling through the royal gardens a century later, Goethe stopped to admire a yellow flower in the bright midday sun. When he blinked and looked away for a moment, a blue flower appeared before his closed eyes — he was seeing the opposite of the real flower, even though he was looking at nothing. (This negative after-image, we now know, when an image is too bright and brief for the retinal ganglion cells that carry signals from the brain to adapt to the changing stimulus.) Here was color not just as a function of light, as Newton had decreed upon unweaving the rainbow with his optics, but a function of the perceiving brain — a collaborative creation of the mind and the world.

Blue is not what we see but what we co-create with ourselves and each other.

Chilean philosophers Humberto Maturana (September 14, 1928–May 6, 2021) and Francisco Varela (September 7, 1946–May 28, 2001) explore this with uncommon subtlety and rigor in their 1984 classic The Tree of Knowledge: The Biological Roots of Human Understanding (public library) — a timeless investigation of “why the apparent firmness of our experiential world suddenly wavers when we look at it up close,” and a timeless invitation “to let go of [our] usual certainties and thus to come into a different biological insight of what it is to be human.”

They write:

The experience of color corresponds to a specific pattern of states of activity in the nervous system which its structure determines … All knowing depends on the structure of the knower [but] the biological roots of knowing cannot be understood only through examining the nervous system… It is necessary to understand how these processes are rooted in the living being as a whole.

Our cognitive understanding may explicate blue, but our embodied experience implicates us in it, binds us both to our biology and to each other:

All cognitive experience involves the knower in a personal way, rooted in their biological structure. There, their experience of certainty is an individual phenomenon blind to the cognitive acts of others, in a solitude which… is transcended only in a world created with those others.

With the central premise that “every act of knowing brings forth a world,” they write:

Our experience is moored to our structure in a binding way. We do not see the “space” of the world; we live our field of vision. We do not see the “colors” of the world; we live our chromatic space… We are experiencing a world. But when we examine more closely how we get to know this world, we invariably find that we cannot separate our history of actions — biological and social — from how this world appears to us. It is so obvious and close that it is very hard to see.

Love, of course, is the deepest way we have of knowing one another. More than a psychological construct, more than a moral imperative, it is part of our creaturely inheritance. Defying the hollow dogma that questions of love are antiscientific, Maturana and Varela write:

To dismiss love as the biological basis of social life, as also the ethical implications of love, would be to turn our back on a history of living beings that is more than 3.5 billion years old… Love is a biological dynamic with deep roots. It is an emotion that defines in the organism a dynamic structural pattern, a stepping stone to interactions that may lead to the operational coherence of social life.

In a lovely biosocial echo of Iris Murdoch’s abiding formulation of love as “the extremely difficult realisation that something other than oneself is real,” Maturana and Varela add:

Biology also shows us that we can expand our cognitive domain. This arises through a novel experience brought forth through reasoning, through the encounter with a stranger, or, more directly, through the expression of a biological interpersonal congruence that lets us see the other person and open up for him room for existence behind us. This act is called love, or, if we prefer a milder expression, the acceptance of the other person beside us in our daily living. This is the biological foundation of social phenomena: without love, without acceptance of others living beside us, there is no social process and, therefore, no humanness. Anything that undermines this acceptance of others, from competency to the possession of truth and on to ideologic certainty, undermines the social process because it undermines the biological process that generates it… Biologically, without love, without acceptance of others, there is no social phenomenon. If we still live together that way, we are living indifference and negation under a pretense of love.

A generation after the paleontologist, philosopher of science, and poet Loren Eiseley arrived at the same conclusion in his breathtakingly beautiful meditation on the first and final truth of life, and a generation before philosopher Iain McGilchrist explored how we render reality through love, they conclude:

We have only the world that we bring forth with others and only love helps us bring it forth.