The Cure

Overview

About two thousand pages across four major parts, logic, natural philosophy, mathematics and metaphysics, written by Ibn Sina, known in Latin as Avicenna, over roughly seven years around 1020 to 1027, and generally regarded as the single largest work of systematic philosophy produced by one author before the modern period. Avicenna was, remarkably, not a professional academic writing at leisure but a practicing court physician and, at various points, a government minister serving different rulers across the fractured political landscape of what is now Iran and Uzbekistan, and later biographical accounts, including a partial autobiography he dictated to a student, describe him composing substantial portions of this encyclopedic project from memory during breaks in an otherwise demanding medical and political career.

The work’s Arabic title, al-Shifa, means healing or cure, in the specific sense of curing the soul of ignorance through systematic philosophical knowledge, and it is organized to cover the entire philosophical curriculum as Avicenna understood it, moving from logic, the tool for correct reasoning, through the natural sciences, physics, biology, psychology, up through mathematics, and finally to metaphysics, the science of being as such and of the first causes of everything else. No complete English translation of the whole encyclopedia exists; the sections most commonly read and assigned, particularly On the Soul from the natural philosophy and the Metaphysics, are available both in standalone editions and in anthologized selections.

Its influence on both the later Islamic philosophical tradition and, through twelfth-century Latin translation undertaken largely in Toledo, on medieval European scholasticism was immense and direct. Aquinas engages closely and repeatedly with Avicennian positions throughout his own work, often adopting Avicenna’s specific formulations even while disagreeing with particular conclusions, and the essence-existence distinction developed in the Metaphysics became one of the standard tools of later medieval philosophy generally.

What happens

Logic. The encyclopedia’s first and, in raw volume, its longest section, working through Aristotelian logic in the tradition established by the late ancient commentators, covering the categories, propositions, the syllogism in exhaustive technical detail, and the various forms of demonstrative, dialectical and rhetorical argument, largely following and extending the structure of Aristotle’s own logical works, the Organon, while incorporating substantial original technical refinement of Avicenna’s own.

Natural philosophy, and On the Soul specifically. The physics section addresses matter, form, motion, place, time, the four elements, and the various levels of natural being, largely within a broadly Aristotelian framework but with Avicenna frequently departing from Aristotle’s specific arguments and conclusions where his own analysis leads him elsewhere, producing an independently reasoned system of natural philosophy rather than simple commentary.

The most widely read portion of the entire encyclopedia falls within this section: the treatise on the soul, addressing psychology in the broad, pre-modern sense of the study of the soul’s nature and faculties. Its most celebrated argument is the flying man thought experiment, in which Avicenna asks the reader to imagine a person created instantaneously, fully formed and mature, but suspended in midair with every sensory channel blocked, seeing nothing, hearing nothing, touching nothing, his own limbs held apart so that not even one part of his body touches another. Such a person, Avicenna argues, deprived of all sensory contact with the external world and even with his own body, would nonetheless immediately and without any inference affirm his own existence, his own self-awareness requiring no evidence drawn from the body at all. Because this self-affirmation persists even when every possible piece of bodily and sensory evidence has been stripped away by the thought experiment’s construction, Avicenna concludes that the soul’s awareness of itself is immediate, not derived from or dependent upon knowledge of the body, and that the soul is therefore not simply identical with the body, an argument with obvious and much-discussed resemblance to, and clear historical priority over, Descartes’s cogito argument developed roughly six centuries later.

Mathematics. A comparatively shorter section covering arithmetic, geometry, astronomy and music, the traditional quadrivium, integrated into the encyclopedia’s overall structure as the intermediate discipline between the physical sciences below and the fully immaterial subject matter of metaphysics above.

Metaphysics. The encyclopedia’s culminating section and, alongside the psychology, the part most read and most historically influential. Its foundational move is a distinction between a thing’s quiddity or essence, what the thing is, and its existence, that the thing is, arguing that these are genuinely distinct in everything except one unique case. For any ordinary thing, a horse, a triangle, a particular person, you can grasp completely what the thing is, its essence, without that grasp by itself telling you whether any such thing actually exists; essence and existence are therefore distinct, and whatever exists, given this distinction, requires some cause external to its own essence to explain why it exists rather than merely being a possible object of thought.

Tracing this causal requirement back through any chain of contingent, caused existents, Avicenna argues the chain cannot regress infinitely without explanation and must terminate in something whose case is entirely different: a being whose essence simply is to exist, requiring no external cause because existence is not distinct from what it is in the first place. This being, which Avicenna calls the Necessary Existent, is the metaphysical foundation from which the existence of everything else, each merely possible in itself, ultimately derives, whether directly or through an extended chain of intermediate causes.

How to read it

Read On the Soul, and specifically the flying man passage, as the natural entry point to the whole encyclopedia. It is short enough to read in an afternoon, self-contained enough to understand without the full logical and physical apparatus that precedes it in the actual text, and it remains genuinely alive as a contribution to philosophy of mind, regularly discussed alongside later arguments of a broadly similar type.

Read the Metaphysics essence-existence argument slowly, working the distinction through with a concrete example of your own, some particular thing whose essence you can state, and asking whether grasping that essence completely tells you anything about whether the thing actually exists. This is the same exercise that makes Aquinas’s later, more compact treatment of the same distinction, in his own On Being and Essence, clear, and reading the two together, Avicenna’s original version and Aquinas’s later adaptation, is genuinely illuminating.

Do not attempt the whole encyclopedia. No complete English translation exists, and even in the original the full text represents a specialized, technical curriculum that professional students of Avicenna’s philosophy spend years working through; the anthologized selections covering the psychology and the central books of the metaphysics give a representative and manageable sample of the work’s most influential and most accessible arguments.

Notice the biographical context as you read. A physician and government minister composing a philosophical encyclopedia of this scale, reportedly drawing heavily on memory during breaks in an active professional and political career, is itself a remarkable fact about the conditions under which this systematic achievement was produced, and it is worth holding in mind alongside the philosophical content itself.

Read this alongside Aquinas’s On Being and Essence and his broader engagement with Avicennian positions throughout the Summa Theologiae, to see directly how thoroughly this originally Arabic philosophical encyclopedia was absorbed into, and continued shaping, the mainstream of later medieval European thought.

Questions it raises

• Does the flying man thought experiment succeed in showing that the soul is not identical with the body, or does it only show that self-awareness does not require attending to bodily sensation, which is a considerably weaker claim?
• How does Avicenna’s flying man compare to Descartes’s later cogito argument, and does recognizing Avicenna’s priority change how the later argument should be understood or credited?
• Is the essence-existence distinction a genuine metaphysical discovery, or a conceptual distinction that does less work than Avicenna’s argument for a Necessary Existent requires it to do?
• Can the chain of caused, contingent existents Avicenna traces really be shown to require termination in a single Necessary Existent, rather than, for instance, an infinite regress or some other structure entirely?
• What does it mean that this encyclopedia was produced by a working physician and political figure rather than a cloistered academic, and does that context change how the text should be read?
• How much of what later medieval Europe took to be distinctively Aristotelian philosophy actually arrived filtered through, and substantially reshaped by, Avicenna’s own independent arguments and departures from Aristotle?