Is Your Mind a Shared Light? Medieval Muslim Thinkers Asked

A Baghdad Scholar Wonders: What Is a Soul?

In ninth-century Baghdad, a scholar named al-Kindî (c. 801–c. 870) sat down to read Aristotle’s book On the Soul. He wanted to understand what makes us think, feel, and know. Is the mind just a part of the body—like the brain—or is it something invisible and separate, a soul? Al-Kindî lived at a time when Muslim thinkers were absorbing Greek science and philosophy. They translated works by Aristotle and Plato, but the versions they read often tried to blend the two thinkers together. Al-Kindî’s ideas ended up mixing two powerful pictures. Aristotle saw the soul as closely tied to the body. Plato claimed the soul is immortal and can know things without the senses.

Al-Kindî believed that the soul is a non-physical substance created by God. When you live a life controlled by reason—pursuing wisdom, justice, and truth—your soul can return home to be near its Creator after death. The very best person even resembles God’s activities, though not God’s innermost essence. While the body is a temporary vehicle, the soul is the real you.

But how does thinking actually work? Al-Kindî was one of the first Muslim philosophers to describe a ladder of intellects. He imagined four stages:

• The First Intellect: a cosmic, always-active mind that holds all universal truths—the species and kinds of things in the world.
• The Potential Intellect: your personal, raw ability to think.
• The Acquired Intellect: the store of ideas you actually learn and keep.
• The Intellect in Act: when you actively think about an idea, your mind unites with that idea, just like the First Intellect is always united with its thoughts.

For al-Kindî, the First Intellect acts like a light bulb that never goes out, shining universal knowledge down to each of us. Our potential intellect receives that light and stores it as acquired knowledge. When we focus on it, we think as that same light. But al-Kindî never fully explained how the imagination—the part of us that pictures things—helps the intellect. This left a gap that later thinkers would try to fill.

Razi’s Three Souls and a World Trapped in Matter

Another early pioneer was Abû Bakr al-Râzî (865–925 or 932), known in the West as Rhazes. He was a famous doctor and a bold philosopher. Razi agreed with Plato that the soul has three parts. He often spoke of them as three separate souls: the rational soul, the animal soul (with its passions and drives), and the vegetative soul (for basic life processes like eating and growing). He placed the vegetative soul in the liver, the animal soul in the heart, and the rational soul in the brain. Yet the rational soul was not the brain itself—it was a non-physical, immortal spirit using the brain as an instrument.

Razi had an unusual idea: the rational soul must free itself from the body and the material world, or else it would be reincarnated into another body—not necessarily a human one. He believed in five eternal cosmic principles, including a world soul that had become trapped in matter and needed divine help to escape. Your own rational soul, he taught, should avoid getting tangled up in physical desires. If it failed, you might come back as a different living being.

Most Muslim thinkers and religious faithful pushed Razi to the margins for his views on reincarnation and his indifference to Islamic teachings. Yet his medical approach—locating mental powers in specific brain organs—set the stage for future philosophers.

The Perfect City’s Hidden Light: Al-Fârâbî’s Active Intellect

A century later, Abû Nasr al-Fârâbî (c. 870–950) wove together Aristotle and Plato into a grand system. He argued that the soul is what makes a living body actually alive. It serves as the body’s form, its driver, and its goal. For humans, the most important part is the theoretical intellect, which strives to understand truths about the universe. The practical intellect, which deals with everyday choices, works as its helper.

Al-Fârâbî introduced an idea that would dominate Islamic philosophy: the Agent Intellect (also called the Active Intellect). This is a separate, immaterial intelligence—the tenth celestial sphere. It pours intelligible forms into our minds, much like the sun illuminates objects for our eyes. Just as sunlight lights up both a visible thing and our eyes, the Agent Intellect energizes both the concepts out there and our potential to understand them. Your potential intellect, at first a blank readiness, receives these universal truths step by step. As you accumulate knowledge, you develop an acquired intellect that more and more resembles the Agent Intellect. Ultimate happiness, for al-Fârâbî, is getting as close to that cosmic mind as possible—though he thought full union was impossible for us.

Al-Fârâbî also gave the imagination a starring role. He saw it as a mimic: it can copy what the senses reported earlier, but it can also imitate the pure intelligible ideas that come from the Agent Intellect. This clever trick explained prophecy. A prophet’s imagination receives divine truths from the Agent Intellect, translates them into vivid images, and passes them to the senses—so the prophet hears and sees revelations as if from outside. It is like a radio picking up a signal and turning it into a voice.

In his view, everyone, men and women alike, has the same intellectual potential. He believed the heart was the ruling organ, powered by innate heat, but the brain assisted the senses and the imagination. Heat differences made men generally more aggressive and women more compassionate, yet he saw no difference in their minds.

Al-Fârâbî left a puzzle: if we never fully join the Agent Intellect, what happens to us after death? He hinted at an afterlife of the perfected intellect, but his arguments were thin.

Avicenna’s Floating Man: Are You More Than Your Body?

Avicenna (980–1037), the most influential of the Muslim philosophers, wanted a watertight proof that the soul is a separate, immortal substance. He invented a famous thought experiment: imagine you are created floating in empty space, with your eyes covered, hearing nothing, touching nothing. You would not see, hear, or feel your own body. Yet, Avicenna says, you would still know that you exist. That “I”—the self-aware ego—must be something immaterial, not dependent on a physical body. So the soul is essentially independent, and death is just the soul losing its body.

Avicenna then asked: how do we think, if the soul is so separate? His answer was to overhaul Aristotle’s internal senses. He placed them in three ventricles of the brain. The common sense in the front ventricle gathers all the raw perceptions from the five senses. Next comes the imagination, which holds onto those pictures. But Avicenna added a new faculty: estimation (wahm). This is an innate ability in both animals and humans to instantly detect a non-visible intention in an object—like a sheep sensing that a wolf is dangerous, or you feeling that a friend is welcoming. Estimation picks up the core character that makes a thing what it is for you at that moment.

Behind estimation sits the cogitative faculty (in humans) or a compositive imagination (in animals). It combines stored images and intentions to plan, judge, and even dream. Finally, memory in the rear ventricle retains these essential intentions for later recall.

Avicenna worried that tying thinking so closely to physical brain parts might threaten the soul’s immortality. So he later tried to separate the intellect from the internal senses. The rational faculty, he argued, does not abstract ideas from the imagination—it receives them straight from the same Agent Intellect that al-Fârâbî described. The steps are: a potential intellect ready to know, an intellect in habitu that has learned but is not using the knowledge, and the acquired intellect actively thinking, eventually conjoined with the Agent Intellect. Most people need sense experience to prepare their souls, but a few gifted individuals—prophets—receive knowledge directly as a holy emanation.

When the body dies, Avicenna insisted, your soul keeps its individual identity, along with all the knowledge and moral character it built. It then experiences eternal pleasure or pain. This made his philosophy more acceptable to religious believers, though it broke sharply from Aristotle’s naturalism.

Averroes: One Intellect for All Humankind?

Averroes (1126–1198), the great commentator from Muslim Spain, thought Avicenna strayed too far from Aristotle. He wanted to return to a more naturalistic view. For him, the soul is not a separate substance injected into the body—it emerges from the body’s organization, like a harmony. The lower faculties (nutrition, senses) serve as matter for the higher ones, with the imagination feeding the rational faculty.

Averroes, like his predecessors, relied on the Agent Intellect to activate our thinking. But he struggled mightily with the question: what is the material intellect—that universal potential for thought in a person? In his early and later works he gave different answers. In his Long Commentary he placed the material intellect as a completely separate, eternal substance—a kind of celestial matter. Together with the Agent Intellect as form, it accounts for all human thought. This meant there is just one material intellect for all people, not a personal one for each of you and me. When you think, your individual imagination and internal senses prepare particular images, and the universal intellect does the actual understanding, connecting to you temporarily.

Averroes introduced a cogitative faculty (fikr) that acts as a bridge between the imagination and the separate intellects. This bodily power abstracts the “intentions” from images and hands them over. He also recognized a passible intellect that is the individual’s own capacity to receive universals, but it is still physical and perishable.

So what happens after death? Since the material intellect is one and eternal, your personal store of ideas dissolves into that single cosmic mind. There is no personal immortality in Averroes’s view—only the eternity of the one intellect. The rare sage who reaches total knowledge might briefly experience a taste of that unity while alive, but it cannot last. This “one-mind” idea provoked fierce debate and was condemned by some religious authorities.

Why This Ancient Tangle Still Matters

These medieval thinkers did not have brain scanners or neuroscience labs, but they asked questions you might recognize. Is your mind just your brain, or is there a non-physical you? When you learn something new, are you downloading ideas from a cosmic database? If you and a friend think the exact same thought about a triangle, does that mean you both tapped into one eternal Triangle concept?

Today, debates about artificial intelligence echo Avicenna’s worry: if thinking depends entirely on physical brain processes, could a machine have a soul? Averroes’s shared-intellect idea feels surprisingly like a cloud server—your local device accesses a universal storage. Even a sheep sensing a wolf’s dangerous intention is not so far from modern ideas about built-in mental modules.

The Islamic philosophers did not settle these questions, but they left you a powerful toolbox of ways to think about yourselves. The next time you ponder whether your inner self is something special or just the hum of neurons, you are stepping into a conversation that began in Baghdad over a thousand years ago.

Think about it

1. Avicenna’s floating man argument says you know you exist even without any senses. Can you imagine a mind that has never sensed anything at all? What would it think about?
2. If Averroes is right that there is only one universal intellect for all humans, would it still make sense to say “my” idea is different from “yours”? Why or why not?
3. Al-Fârâbî believed the Agent Intellect sends ideas to prophets’ imaginations. If you received a sudden brilliant insight in a dream, how would you know whether it came from your own brain or from a cosmic mind?