Three Brains & Three Disciplines
Three Brains & Three Disciplines
An Overview

Robert Campbell
June 2015
Our spiritual character is assessed. Emotional patterns of an archetypal nature, associated with our ancient limbic
brain, are reflected in both hemispheres of our neocortex or new brain. Our mute right brain tailors them according
to timeless holistic themes that we entertain as frameworks of understanding essential to making sense of our
sensory experience, often along fixed religious, ethnic, or cultural lines. Our rational left brain employs language to
develop techniques of behavioural response accordingly. Our three brains thus have very different functions yet are
constrained to live in the same house together, introducing the schizophrenic streak so evident in our tragic history.
The anecdote for this is the practice of three distinct but mutually related disciplines, namely a left brain physical
discipline, a limbic brain moral discipline, and a timeless right brain spiritual discipline. Only in this way can we hope
to bring our three brains into a sustainable balance with the cosmic order by which we have evolved.

Our Spiritual Nature:
Despite claims by some scientists that human consciousness is an emergent property of physics, all human
experience has a spiritual character. Most of us do not think of it as such. We tend to take our experience of the
world we live in for granted and we believe that the things that we see and sense around us constitute physical
reality shared by us all in what may be called the public domain. Some of us may engage in spiritual practices of
various kinds, meditation, prayer, and so on, and some of us are members of formal religious institutions. In fact
most of the world believes that there is a transcending holistic reality of some kind that is timeless or eternal.

Nevertheless some of us believe that it is all a fortuitous accident without meaning or purpose. Some believe that we
have evolved solely by a long series of random mutations, a few of which are favoured by natural selection. (1)
Even so, few of these same believers or disbelievers would deny that we have spirit. We know that we are animated
by energy patterns of an emotional nature that we can consciously observe. (2) Despite differing interpretations it is
hard to deny that we are indebted to historically integrated animating patterns of behaviour that are archetypal in
nature and that derive from our cultural and natural heritage reaching back millions of years. It is in this context that
our personal experiences evolve according to how we place our values. (3)  

Three Brains:
Values such as truth, love, mercy and justice are not physical things that exist out there in a world of form made of
atoms and molecules. Values do not belong to the public domain, although they may find a general cultural
consensus in various cases. Values belong to the private domain. They are mercurial and context dependent
emotional perceptions of our ancient Limbic brain (4). Our emotional experience is extremely complex and diverse.
These emotional patterns fuel both right and left hemispheres of our neo-cortex or new brain. These three brains
are mutually independent in the way they function, yet they are mutually related.(5)
       Figure 1a                                                                         Figure 1b
Cross section through brain centre                                            Side view with brain stem and cerebellum removed
The most ancient reptilian part of our limbic cortex is primary to memory or recall consistent with sensory input.(6)
Our right brain intuitively integrates emotionally patterned memories that are recalled relevant to sensory input.
The emotional urges to act may not be fully consistent with the best course of action. We have an intuitive sense of
what kind of general response may be appropriate to circumstance. A repertoire intuitively presents itself as more
or less fitting to circumstance that allows of some tailoring to suit a holistic framework of understanding that we
entertain. This comes as an intuitive right brain theme that guides our rational left brain in determining a specific
behavioural response.

If the sensory circumstance is familiar the response may be spontaneous. If it is unfamiliar we may need time to
reason out a response consistent with the theme that tailors the emotional pattern evoked by the sensory input.
Using left brain language we may thus reason out a plan of action that is fueled by intuitively tailored emotion. For
example an insult may arouse emotions to retaliate in kind, but we may intuitively sense that it would make things
worse. The initial emotional impulse is intuitively modified by the right brain to a more positive theme. Our left brain
thus works out a technique of response that attempts to defuse the situation amicably. (7) If the sensory input is
unfamiliar and also recalls emotional patterns that are contrary to the theme of our integrating framework of
understanding we may respond spontaneously in socially inappropriate ways. These are crimes of passion. We all
seek a feeling of unity, a feeling of being whole. We have to bridge this Rift in Wholeness between Self and Other
than self. In extreme cases a quest for that seductive feeling of unity can resolve itself in emotionally identifying
with a common theme expressed in language to the exclusion of the rest of humanity.

The screams of Hitler captured a nation in global conflict. The Islamic State movement is a brutal interpretation of
Islam as the only true religion, all others being infidels, including Islamic sects that may not comply. Christianity has
had some tragic periods of violence based on spurious interpretations of the Bible that are completely contrary to
the teachings of Jesus. By finding that seductive feeling of unity in an exclusive nationalist, social, or religious
cause we effectively exclude ourselves from the rest of humanity to our spiritual detriment. There is a tragic
paranoid streak evident throughout the history of human civilization.(8)(9)(10)(11)

Developing Frameworks of Understanding:
We are born with a certain orientation and talents, certain themes along certain lines, and we evolve them further
from childhood. We absorb elements of them from our elders and peers: parents, teachers, religious leaders,
playmates, associates, friends and enemies. From many sources we gradually develop and refine integrating
frameworks of understanding consistent with right brain themes that appeal to us at an intuitive level as a human
being. We hardly notice it happening because this semi-subliminal process is mute.

We are also subject to overriding cultural frameworks that are culturally imposed in various ways. These may take
the form of nationalist or ethnic themes, political themes, religious themes and so on. These too often become
exclusive themes employing that seductive pursuit of unity by emotionally identifying with the theme to experience
the supremacy of Self over Other. “I’m the King of the Castle and you’re the dirty rascal,” is the same old game we
played as young children. The Rift between Self and Other is bridged within the group. But sadly our common
humanity is subverted to exclusive ideals implicit in the theme. Too often we believe that we are special. We tend  
to contrive two sets of thematic rules, one set for ourselves and another set for others. Too many of us claim they
are self made men and worship their maker, as the saying goes.

Whatever their nature we assume archetypal frameworks of understanding (12) that we expect our experience to
conform to. Our holistic right brain demands that we must have these integrating themes. Everyone has them.
They are subject to change only with great difficulty precisely because we need them to make sense of our
experience. They have boundless and timeless characteristics that predetermine the general themes of our
responses to various circumstances that we encounter. We may switch between different integrating archetypal
frameworks in different circumstances without noticing the inconsistencies between them. The human race has
always had a deeply embedded schizophrenic streak. This has to do with how our three brains are structured to
function in independent yet mutually related ways.

If we reflect carefully on this we must acknowledge that we implicitly believe that there are Universal Values that
apply to us all whether we can access them or not. We claim our personal perception of them to be true whether
they are true or not, because our perception of values depends on anciently rooted emotional patterns that are
essential to our integrating frameworks of understanding. Even if we believe that there are no universal values we
must believe that this is true for every sentient creature in the universe, precisely because our right brain
integrating framework is holistic. We do not see the contradiction in claiming that there is no universal truth to be
universally true. And we can not reasonably believe that we are the only ones to whom universal values do not
apply. What we believe that applies to us we must believe applies to everyone everywhere. Whether we know it or
not we are talking about the cosmic order, whatever we believe. By denying universal truth transcending creation
we implicitly proclaim ourselves the Supreme Authority over all Beings. There can be no God but Self. To
acknowledge Truth as Universally transcendent and Other than Self requires humility. Like all values humility is  
the province of our Limbic Brain, however it is conditioned by our conscious experience including humiliation

Our Limbic Brain has a capacity to reflect on itself. The brain of the lower mammals in humans is associated with
the cingulate gyrus that overrides the hippocampal gyri associated with the reptiles thus imparting a capacity for
emotional reflection. The horse can reflect on the more primal appetites of the crocodile, so to speak. Both
constitute the limbic cortex that is intimately connected to the autonomic nervous system. The latter is generally
taken to include the enteric nervous system that has invertebrate origins that predate the vertebrates. Thus
dependent on our animal ancestry over the sweep of our evolutionary history, we have been invested with three
brains that allow us to create our own essential character in our journey through life. This determines how we tailor
archetypal emotional patterns of behaviour in the public domain.

The Public Domain:
The public domain consists of what all of us implicitly agree on that exists out there in the world around us. This
external objective reality is not really “out there” however. Our sense perceptions of the objective world are
integrated by our nervous systems into a subjective virtual reality that mirrors the external surfaces that we see
and sense as things and people and that we perceive to be “out there.” In fact all we can ever know is active
interface processes between a universal inside and a universal outside, neither of which can be known to the
exclusion of the other. Reflected light from physical objects enters the retina of our eyes and interface processes
between neurons in our brain reconstruct our virtual reality.

This virtual reconstruction of the objective world that we each subjectively perceive from our own unique
perspective allows us to independently navigate and behave in relation to it. We each live in our own virtual reality
that we interpret according to how we each place our values. We are more than flesh and blood. We are also
spiritual beings, albeit anchored to the flesh as long as we inhabit it. It is in this way that we are enabled to learn
from experience and determine our own evolution.

We also have a capacity to sense the emotional intentions of others in the way they behave. This includes other
animals, because we share ordered archetypal patterns of behaviour throughout the quadruped vertebrate
lineage reaching back 370 million years. In fact our enteric nervous system that lines our ten meter gut from mouth
to anus has origins predating the vertebrates. Although it is usually considered part of the autonomic nervous
system it has been called a second brain because it can function independently.(13) It has some 100 million
neurons, more than in the spinal column or the peripheral nervous system. Over 90% of the vagus nerve, the
parasympathetic supply to most of the visceral organs, is devoted to enteric nerves that inform the brain. They can
make us feel squeamish, deeply repulsed, nauseous, hungry, or fulfilled. Within these constraints of integrating
values and tailored emotional patterns, we determine the character of our behaviour and our destiny. In doing so
we are indebted to our animal history in the biosphere

Our Ancient Limbic Brain:
The instrument that we all use to meaningfully integrate and make sense of our phenomenal experience is our
Central Nervous System which includes our spinal cord and head brain. Although both cerebral hemispheres
receive symmetrical sensory input there are fundamentally important functional divisions. The limb or edge of  
both hemispheres is similar in cytological structure to the ancient brains of the reptiles and lower mammals.(4)

In humans the huge expansion of the new part of the cortex has curled the old part inward around the top of the
brain stem at the top of the spinal cord. Together with related structures, especially the hypothalamus, this ancient
limbic cortex constitutes the Limbic System that is intimately associated with our emotional apparatus, the
autonomic nervous system.

This functionally integrated brain is ancient, with origins dating back to the appearance of the first quadruped
amphibians about 370 million years ago. Overriding this ancient emotional brain, the new brain or neo-cortex has
expanded over it to provide humans with a vastly superior intellectual capacity that is not itself emotionally
coloured. Our new brain nevertheless reflects emotional patterns in conscious awareness and yet it has no
significant biological controls over the old emotional brain. Dr. P.D. MacLean who did much of the research on the
physiology of this arrangement called it a built-in Schizophysiology.(14) Our intellectual capacity to build weapons
of mass destruction is harnessed to the emotional capacity of a crocodile and a horse. Human history attests to
our paranoid streak that is still so evident today.

Our New Brain - the Neocortex:
Our new brains are further divided into four major functional quadrants. The rear half of the neocortex integrates
sensory input for both sides of the body. The front half accommodates the assimilation of motor responses to
sensory input. The right hemisphere intuitively integrates meaning holistically. We need an integrating framework
of understanding that is intuitively perceived and mute. The intuitive perception of structural wholeness has a
timeless character. It concerns the Ontological Structure of Being. This right brain has no capacity to speak in right
handed people. It cannot initiate actions apart from repetitive actions symmetrical with the left brain, such as in
walking or running, and this is largely automated in our formative years by delegation to the spinal cord brain.
                   Figure 2a (15)                                                           Figure 2b
           Topology of the monkey brain is similar to humans.                              Simple Top View: Primary & Secondary motor-sensory areas
Note: Secondary polarities are nested within each hemisphere. A further indication of how the cosmic order elaborates within itself is
that each sensory point in the Sensory topology areas has a motor surround and likewise each Motor point in the motor topology
areas has a sensory surround. This is clear evidence that sensory integration has a polar relationship to motor function, and
conversely that motor integration has a polar relationship to sensory function. It further indicates how the cosmic order proliferates in
nested levels within itself. See the
Two Faces of Our Three Brains.

The left hemisphere employs language to assimilate techniques of behaviour by drawing on knowledge gained
from phenomenal experience. It employs Epistemological Knowledge of Phenomenal Behaviour as distinct from
right brain intuitive perception of the timeless Ontological Structure of Being. So the four quadrants are related to
Sensory input with respect to Motor output, back to front respectively, and Intuitive Insight with respect to the
Language and physical Behaviour, right half to left half respectively.

Both hemispheres have Major Sensory and Motor areas and Minor Sensory and Motor areas. This provides two
polar relationships in each that allow each hemisphere to function independently of the other hemisphere, in
relation to the common emotional limbic brain polarity which can also function independently. The three polar
relationships essential to mental activity (9) are structurally evident at a subsumed level with respect to each
hemisphere, just as they are evident at a subsuming level as when the brain as a whole employs the primary
Sensory and Motor Areas in each hemispheres in relation to the common limbic polarity. Our three brains can
function independently, function as separate right and left halves both anchored to common emotional patterns,
and also function together in a mutually interdependent way. Since they are constrained to live in the same house
together, however, our three brains often do not get along. A completely sustainable balance between our three
brains generally eludes us.
Figure 3

The Human Dilemma:
Herein lies the crux of the human dilemma. Our right brain insight into the timeless Ontological Structure of Being is
seriously deficient. In fact it has deteriorated since ancient spirit cultures sought harmony with nature. The
Ontological Structure of all Being is the Cosmic Order sought by humans throughout our history. With the
emergence of complex civilizations came empire building and conflict which has reached global proportions with the
cultural meltdown that began a few centuries ago, culminating in two world wars with many lesser wars and
insurrections evident today.

But whether it has been called Rta in the ancient Vedic tradition of the Indus valley, Maat in Ancient Egypt, Me in
Mesopotamia, the Dharma in India, the Tao in China, or God in Western traditions all these words refer to the
cosmic order as a timeless moral order transcending our short sojourn on planet Earth. The cosmic order was
historically conceived as a living manifestation of Universal Values which since ancient times has been associated
with the One Supreme Source of All Being transcending the whole of physical existence, while also exhibiting
evolutionary variants implicit within creation.

Universal Values do not exist as mere intellectual abstractions. That would make them arbitrary creations of the
human mind subject to change. To be universal they must timelessly transcend this physical existence. To be
timeless, universal truth, mercy, compassion, love, justice must be mutually harmonious unto themselves as a living
whole. As such they are the living manifestation of ultimate reality. The ultimate reality must be One in order for us
to integrate experience holistically and value judgements are essential to this end. In other words Universal Values
are manifest in One Supreme Living Being that transcends and subsumes creation. Otherwise they would have no
universal meaning. Universal Truth is synonymous with God in this respect. (16) The multiplicity of phenomena that
we experience in flux is a subsumed elaboration of Universal Wholeness that allows both evolutionary and
degenerate variants of the cosmic order. This allows us to learn from experience and evolve.

Three Disciplines:
In summary the world we each live in is a virtual reconstruction in our mind of the objective world we perceive with
our senses from our own unique subjective perspective. It is to this world that our left brain develops explicit
techniques of physical behaviour. Our subjective world is coloured by our history, by how our values evolve and find
emotional expression via our limbic brain. Our subjective world is also holistically determined by integrating intuitive
right brain themes that we entertain. Each of our three brains, although mutually related, is involved in a distinct
separate endeavour. This brings us to three distinct disciplines that are necessarily involved. (17)

(1) Physical and Social Disciple:
Of primary importance is the physical discipline. We must look after the needs of this physical body that we find
ourselves the proprietor of. We must feed clothe and house it and attend to the needs of our family. We must
accept a community of friends and acquaintances. This requires that we work to make a responsible contribution of
value to our collective human benefit in the global market place. If we seek to do this in an honest sustainable way
we must find employment that enables it. We must also regulate our activities, avoid socially inappropriate  
practices, make reasonable efforts to get along with others, eat properly, maintain healthy habits, and so on. The
physical discipline is primary to our survival. It concerns how we explicitly behave and make our social  
commitments. We must find a constructive vocation and carefully practice it with good intension. “Social success” is
not a criterion. A common labourer may be better placed than a corporate executive drawing huge bonuses.

(2) Moral Discipline:
The moral discipline is an emotional concern with how we place our values. We must moderate our animal  
appetites by training our horse to manage our crocodile. This requires careful observation of the spirit in which we
undertake actions. It is not just what we do that matters. It is also the intension behind our behaviour that matters.
We tend to react in pride, anger, hate, spite, greed, disdain and so on. We tend to practice deceit and self
gratification sometimes with malicious intent. Unmonitored and unchecked our emotional brain claims dominion of
our mind and erodes our character. We have to work at recognizing the countless faces of moral erosion. We can
redeem deceit with honesty, pride with humility, anger with tolerance, hate with compassion, spite with patience,
greed with benevolence, disdain with respect, and so on. Because our emotions are reflected in conscious
awareness we can observe their many subtle nuances and modify their expression. We must be especially careful
to recognize and curtail every tendency to emotionally identify with ethnic, national, political, social, and religious
ideals that may claim ascendancy of Self over Others. We must avoid making them ends unto themselves. In
summary this means avoiding emotional identification with likes and dislikes. We must seek ways of living right life.
This requires a discriminating capacity for reflection on one's actions and motives. Our common humanity
subsumes the evolution of life in the biosphere. Human organizations of all kinds are properly vehicles to make a
constructive contribution to our common humanity, and by extension to the biosphere.

(3) Spiritual Discipline:
The physical and moral disciplines, practiced with diligence, provide an essential foundation for the spiritual disciple.
The spiritual discipline is a persistent quest for Universal Truth transcending creation. Rational belief systems
based on language must be set aside. The quest must be open. It cannot be preconditioned by language. It is an
intensive right brain search for the roots of meaning. This requires that the left brain dialogue that normally goes on
incessantly in our minds should be stilled. The sympathetic division of our autonomic nervous system normally
feeds our language hemisphere keeping it busy in an often inane internal dialogue. One technique to stall this
process is to count one’s breaths, since breathing is an autonomic function that we have conscious access to. By
focusing language on each breath this helps us to stall the mental dialogue, thus stilling the sympathetic division
that fuels immediate thought and action. This allows the parasympathetic division that works in accord with right
brain intuition to respond to the quest. More fundamental archetypal patterns can be aroused and accessed in this  
way, simply by an intensive wordless quest into the nature of truth. There is a content implicit in the concept of
Universal Truth that is the object of meditation. One can come to visually see one’s personal archetype, to
experience union with the biosphere, and ultimately to actually see and experience Universal Truth as a living reality
transcending all creation. An intensive and persistent quest of this kind into the nature of All Being takes a very
strong mind with a firm moral and physical foundation. We each have an independent relationship to Supreme
Being as the ultimate realization of Universal Truth. One's religious persuasion can become an obstacle rather than
an asset if we emotionally identify with left-brain language in books, although books can help if studied in the right
way. Even if we do not get to know Universal Truth directly, progress along the way will develop an intuitive
awareness behind our mental and emotional processes  that allows us to respond more constructively in more
spontaneous and appropriate ways.

Our Personal Context:
In summary the world we each live in is thus a virtual reconstruction of the objective world in our mind from our own
unique subjective perspective. It is coloured by our history and how we place our values. It is determined by our
world view and how we make our commitments accordingly. We each have a story that relates to how we perceive
the cosmic order to work. All we can really talk about with authority is the insights we have gained from our personal
experience. Our religions and sciences may attempt to give an account of the cosmic order in language, however
we have seen that language is confined to our left brain physical discipline. Their social relevance, however
valuable, does not extend to a direct personal perception of Universal Truth. Belief in words is not the same as
knowing in direct phenomenal experience.

Languages of all kinds have evolved to help us cope collectively with the flux of objective circumstance that we each
find ourselves in. They are not suited to the timeless and boundless realm of the cosmic order. For example,
despite many dissenters and evidence to the contrary, Big Bang cosmology is preached as gospel to a trusting
public. Measurements of space and time derived from creation are raised to a priori status to explain their own
creation, yet this implicit contradiction is ignored. And there are surely few among us today who believe with Isaac
Newton that the world was created about 4,000 BC by adding up all the generations listed in the Bible. It is
extraordinary that the founder of modern physics should have held such beliefs. Nevertheless there is no denying
his huge contribution.  

In this realm all we have to depend upon is our mute intuitive perceptions of the Ontological Structure of Being.
Primary to this perspective is the factual realization that all we can ever know is active interface processes between
a Universal Inside and a Universal Outside, neither of which can be known to the exclusion of the other. The only
things we can ever know are active interface processes. (18) This is the only boundary condition consistent with
Universal Wholeness. In all of our endeavours, good or bad, we seek to mutually reconcile inside and outside in
some meaningful way, according to how we make our commitments. In other words we seek to balance our
subjective ideas with their objective realization through our creative efforts.

This always creates a bridge between Self and Other that may or may not have exclusive characteristics. Such
reconciliation is implicitly timeless and boundless with respect to our personal archetype, although it is subject to
recall and refinement as we develop and evolve our character. To the extent that we make commitments of eternal
value we can bring our three brains to a sustainable balance that determines our spiritual destiny.

Notes & References:
  1. Dawkins R. River Out Of Eden, New York Basic Books, New York, 1995.
  2. Papez JW. A proposed mechanism of emotion. 1937. J Neuropsychiatry Clin Neurosci. 1995;7(1):103-12.
  3. Recent research on epigenetic factors that alter gene expression without altering the DNA structure of
    genes themselves are eroding at the strict Darwinian interpretation. Behavioral tendencies are heritable
    and not random. See Carey N. The Epigenetics Revolution: How Modern Biology is Rewriting Our
    Understanding of Genetics, Disease and Inheritance. London: Icon Books, 2012.
  4. Broca, P. Anatomie compare des circonvolutions cerebrales: le grand lobe limbique. Rev. Anthropol.1878;  
  5. Sperry RW. Hemisphere deconnection and unity in conscious awareness. Am Psych. 1968 Oct; 23(10):723-
  6. MacLean PD (1990) The Triune Brain in Evolution: Role in Paleocerebral Functions. NY: Plenum Press
  7. We know this from personal experience.
  8. MacLean P.D. (1952). Some psychiatric implications of physiological studies on frontotemporal portion of
    limbic system (visceral brain). Electroencephalography and Clinical Neurophysiology 4 (4): 407
  9. Campbell R.
  10. Koestler A. The Ghost in the Machine, London: Hutchinson (1967); Picador Edition 1975-1981.
  11. Campbell R.  
  12. Jung C.G. Jung C.G. The Archetypes and The Collective Unconscious. In: The Collected Works of C. G.
    Jung Vol. 9 Part 1. London: Routledge, 1980.
  13. Furness J.B. The Enteric Nervous System. John Wiley & Sons, 2008.
  14. MacLean PD. Psychosomatic disease and the visceral brain; recent developments bearing on the Papez
    theory of emotion. Psychosom Med 1949; 11:338 - 53; PMID: 15410445 [CrossRef]
  15. Woolsey CN. Cerebral Localization and Organization. Shaltenbrand G, Woolsey CN, Eds. University of
    Wisconsin Press, 1964.
  16. Campbell R. .
  17. The three disciplines were first expressed and taught by Sri Govindananda Bharati known as the Shivapuri
    Baba, a Hindu who achieved God realization after meditating alone in the forest for 25 years. He spent
    another four decades walking around the world to fulfill a promise to his grandfather who had given him
    some valuable gems atones to finance his journey across oceans and so on. He met many famous people
    including Queen Emma of the Netherlands, Kaiser Wilhelm II and other heads of state.  He had many
    personal visits with Queen Victoria who asked him to stay in Britain until she died, which he did. He also met
    George Bernard Shaw, Theodore Roosevelt, the dictator Porfirio Diaz of Mexico and various others,
    completing his journey in 1915. He died in 1963 at the age of 137. He refused to be a guru with a following
    of admiring believers but responded to questions from genuine seekers of Truth. A stone building has been
    erected over his grave not far from the airport at Kathmandu. J.G. Bennett met him twice the last year of his
    life and wrote Long Pilgrimage,  Hodder and Stoughton, London, 1965.
  18. What the author calls the System of delineating the cosmic order exhausts all possible structural
    relationships of inside to outside in an open ended nested hierarchy of higher Systems such that the lower
    Systems transcend and subsume the higher Systems that elaborate on them. Intuitively questioning the
    meaning implicit in each Term of the System can be a valuable aid in one's quest for Universal Truth which
    is represented by System 1. The cosmic order was revealed to the author in this way through a series of
    cosmic insights transcending creation that came over a period of a few decades. http://www.cosmic- .
System 4
System 4 Terms
The Nervous System - Part 2 - Cerebellum
Language, 3 Races, 3 Brains
System 3
Nervous System - Part 1 - Spinal Cord
Inside Our Three Brains
Introduction to the System
The Two Faces of Our Three Brains