Every philosophy has to decide how far the question why extends. Ask it of a falling stone and it answers readily; ask it of a theorem, and it answers differently but still answers; ask it of the world entire, and the philosopher must either supply a ground or explain why the question has run out of territory. Arthur Schopenhauer built his first book around that decision. Omar Khayyam, seven centuries earlier, arrived at the same boundary and did something Schopenhauer did not do: he stopped.
This article compares them on that question alone. It is not a comparison of pessimisms; that parallel has been examined already in this series, and it has the disadvantage of being the obvious one. The more interesting convergence lies in the theory of grounds — what a reason is, how far it reaches, and what a philosopher does at the point where it fails. On the first two questions the two men agree to a degree that is genuinely surprising. On the third they diverge, and not in the direction one would expect: it is the eleventh-century mathematician who holds the line, and the nineteenth-century critic of metaphysics who crosses it.
I. Schopenhauer’s Four Roots
Schopenhauer’s doctoral dissertation, On the Fourfold Root of the Principle of Sufficient Reason (1813), begins from Leibniz’s formula — nothing is without a reason why it is rather than is not — and makes an observation the formula conceals. The word reason is doing four different jobs. There is the ground of becoming, which is causality and governs changes in physical states. There is the ground of knowing, the logical warrant that makes a judgement true. There is the ground of being, the relation of parts in space and time that underwrites geometry and arithmetic. And there is the ground of acting, the law of motivation, which is causality observed from the inside, in one’s own willing.
The four are irreducible to one another, and Schopenhauer’s charge against his predecessors is that the great metaphysical proofs live in the confusion between them — sliding from a logical ground to a physical cause, or from a cause to a purpose, and calling the result a demonstration.
The consequence that matters here is structural. For Schopenhauer the principle is not a law the world obeys; it is the form of our cognition, the shape of representation itself. It therefore holds everywhere within experience and nowhere outside it. And since what he takes to be the inner nature of the world — will — is not a representation, it stands outside the principle altogether. The will is grundlos: groundless, not in the sense of being erratic in its operations, but in the strict sense that the question why has no purchase on it. It is not the last link in the chain. It is the thing the chain was never attached to.
Hold on to one feature of that position, because the rest of this article turns on it. Having established that cognition cannot reach beyond representation, Schopenhauer proceeds to tell us what lies beyond it. He names it. He describes its character — single, aimless, insatiable, without knowledge or purpose — and builds two volumes on the description. The boundary is drawn, and then a report is filed from the far side of it.
II. The Chain of Order, and Who Is Speaking
Khayyam has no treatise on the principle of sufficient reason, and the phrase would have meant nothing to him. What his treatises contain is the principle itself, stated as plainly as any scholastic ever stated it. From Risāla dar ʿIlm Kulliyāt-e Wujūd:
That which is the effect of some thing must inevitably have a further cause, and this rule they call “the chain of order.”
Around that rule stands the full Avicennan apparatus. Whatever can be thought is necessary, possible, or impossible; the necessary is what cannot not-be; the possible is whatever exists apart from the Creator; and from the impossibility of a series of possibles sustaining itself, the Necessary Being follows as First Cause. The treatise then descends through the ten Intellects, the Souls, the spheres, the elements, and the offspring, each rank the effect of the one above it.
It is tempting to read this as Khayyam’s metaphysics, and most comparative treatments do. The text discourages it. The treatise announces itself in its opening lines as a commission — a patron asked him for “some lasting keepsake in the science of the universals,” and this is the keepsake: an exposition of a received science, written to order. Its characteristic verbs are reporting verbs. This rule they call the chain of order. The sages have given some of those forms the name “property.” Khayyam is setting out what the discipline holds, in the voice of a man setting out what the discipline holds.
And where he is asked to go further, he declines in so many words. In Risāla fī al-Kawn wa al-Taklīf, having laid out the philosophers’ account of why creation descends in ranks and why contraries exist, he closes the exposition by stepping back from it: if these proofs bring you to certainty, then follow them — but he does not add his own opinion, and passes the truth of these matters over to sound and robust reasoning. The sentence is easy to read past. It should not be. At the exact point where the argument would become a personal commitment, Khayyam withholds the commitment and hands the question on.
This changes what can be claimed about him. The chain of order is doctrine he transmits with great precision and does not underwrite. He is not a man who runs the contingency argument and rests on its conclusion; he is a man who can state the argument better than most of its adherents and who declines to say whether it works.
III. The Shared Restriction
The declining is not incidental. In the third chapter of the Universals, Khayyam sorts those who seek knowledge of God into four groups and fails two of them outright. The theologians settle for dialectic and persuasion. The philosophers and sages, who “sought knowledge by purely rational proofs under the laws of logic” and refused anything less, “could not fulfill the conditions of logic, and proved incapable of it.”
The verdict is remarkable in its setting. Khayyam belongs to that second group and is writing, at that moment, a treatise of exactly the kind the second group writes. What he ranks highest is the fourth way, the Sufi one, which proceeds “not by thought and reflection” but by purification of the rational soul until the realities stand forth directly.
Strip away the vocabulary and the shape is Schopenhauer’s. The apparatus of grounds operates within a domain; at the boundary it does not become difficult but inapplicable; and whatever lies beyond is reached, if at all, without inference. Two philosophers, each trained to the highest standard of demonstration available in his century, each concluding that demonstration does not reach the thing that matters most, and each nominating a non-inferential route in its place.
The quatrains state the restriction more bluntly than any treatise could:
My reason’s depth affords You no demonstration;
Quatrain no. 11
and all my thought is only supplication;
how should I know Your essence as I ought? —
none knows Your essence but that essence’s contemplation.
The third line is a technical admission dressed as a rhetorical question, and the fourth closes the circuit: the essence is known only by the essence’s own act. No human faculty appears on the list. The same limit opens another quatrain — “O You, whom reason’s reach can never find” (no. 1) — and recurs where knowledge itself is said to be refused to reason (no. 14).
IV. The Crossing One Makes and the Other Refuses
Schopenhauer’s most famous application of his own restriction is his demolition of the cosmological proof. The proof, he argued, is invalid in principle rather than in detail: it applies the principle of sufficient reason to every contingent thing until it arrives at a first cause, and then declines to apply it any further. Causality, he objected, is not so obliging as to let itself be used “like a cab which we dismiss after we arrive.” Either the principle holds universally, in which case the first cause requires a cause and nothing has been proved, or it holds only within experience, in which case it was never entitled to argue beyond experience at all.
The natural assumption is that this objection lands on Khayyam, whose treatise contains the very inference Schopenhauer is attacking. It does not, and the reason is the withholding described above. Khayyam reports the ride; he does not take it. The one place where he might have endorsed the destination is the place where he sets down his pen and passes the matter to sounder reasoning than his own. Whatever else the quatrains contain, they contain no Necessary Being arrived at by argument — and when the same question appears in verse, what comes back is not an answer but a reckoning of the attempt:
My heart was never kept from learning’s sphere;
Quatrain no. 54
Few were the secrets that did not draw near;
For seventy-two years I pondered, night and day—
It became clear to me that nothing to me is clear.
This is not a lament about laziness or bad luck. It is a result, stated in the form a result is stated in: the inquiry was maximal, the access to the material was excellent, the duration was a lifetime, and the finding is negative. A man who had arrived at the Necessary Being by demonstration and rested there could not write that line.
Now turn the objection around, which is where the comparison becomes uncomfortable for Schopenhauer. He forbids the crossing and then makes one. Having argued that cognition is confined to representation, he identifies what lies outside representation as will, characterises it, and reasons about it at book length — on the strength of a privileged inner access that he claims, but that his own epistemology has no obvious room for. Critics from Nietzsche onward have pressed exactly this point: the thing-in-itself, having been declared unreachable by the principle of sufficient reason, is reached anyway and given a name. Schopenhauer’s cab is not the cosmological one. It is a different vehicle travelling the same forbidden road.
Khayyam takes neither. He marks the boundary, reports what the tradition says lies past it, states that the tradition’s method fails there, declines to give his own verdict, and in the quatrains records that a lifetime of inquiry produced nothing that could be called knowledge. Judged by Schopenhauer’s own rule — that the principle of sufficient reason may not be used to travel beyond the domain in which it is valid — Khayyam applies the rule more consistently than the man who formulated it.
V. Why the Silence Is Not Ignorance
A refusal to answer can be mere absence of an answer. Khayyam’s is not, and one quatrain shows why:
The secrets of eternity, Neither you know nor I
Quatrain no. 30
And this enigmatic discourse, neither you read nor I.
Behind the veil lies the conversation of you and I,
But when the veil lifts, neither you remain nor I.
The first two lines set the limit. The last two explain it, and the explanation is structural rather than circumstantial. Our entire discourse — the questioning, the proofs, the disagreement — takes place on this side of a veil. Lift it, and the conversation does not continue in better light: the parties to it cease to exist. There is no standpoint from which the answer could be received, because receiving it would require a knower, and the unveiling dissolves the knower. The limit is not a shortage of evidence or a failure of method. It is a fact about the architecture of the situation, and it holds for the clever and the pious alike.
Set that beside Schopenhauer and the two thinkers are, extraordinarily, working the same image with the same content. The veil is his too — the veil of Māyā, which he took from the Upanishads and identified with the principle of individuation, the space and time that separate one thing from another and constitute the world as representation. He holds, exactly as the quatrain does, that when the veil is penetrated individuality is not preserved: the boundary between self and other falls, which for him is the ground of compassion and the beginning of the saint’s renunciation.
The premise is shared and the conclusion is opposite. Both men say that lifting the veil abolishes the individual. Schopenhauer treats that abolition as the route to the deepest knowledge available to a human being, the one condition in which the world’s inner nature is apprehended. Khayyam treats it as the precise reason no such knowledge can be delivered: whatever is on the other side, there is no one left to bring it back. One philosopher’s gateway is the other’s proof that the gate leads nowhere a person can return from.
VI. Where Explanation Halts
A smaller parallel deserves recording, because it shows the two men reasoning in almost identical terms about the terminus of causal explanation.
In the second chapter of the Universals, Khayyam asks why bodies alike in corporeality produce unlike effects, and answers that forms and powers must be affirmed within them. He then anticipates the objection that this is mysterious and disposes of it by an appeal to habit:
Were it not that fire is commonly seen, and that through the frequency of seeing it its strangeness and wonder have faded, the body of fire would be the strangest and most wondrous of all things.
The magnet draws iron; a single flame kindles a hundred thousand without diminishing. We do not find these strange, and our not finding them strange is a fact about familiarity rather than about the world. The power is simply there, and explanation terminates in it.
Schopenhauer makes both moves. Etiology, he argues, explains only the succession of states and never the original force according to which the succession proceeds; and he observes, as Khayyam does, that the commonness of a phenomenon disguises the fact that nothing about it has been explained. Where they differ is what to do at the terminus. Khayyam treats the irreducible power as a datum — know that it is there, and be freed from many perplexities. Schopenhauer treats it as the seam where the world’s inner nature shows through, and identifies natural forces as immediate objectifications of will. The observation is shared. The metaphysics built on it is the crossing Khayyam declines to make.
VII. One Position, Two Genres
Comparative studies of Khayyam habitually posit two Khayyams: the orthodox philosopher of the treatises and the sceptic of the quatrains, with a good deal of ingenuity spent on deciding which is the real one. The reading advanced here does not need the split. What the treatises do is expound a received science with great precision and withhold assent at the point where assent would be required. What the quatrains do is state that withholding in the first person, without the professional courtesies:
Those who at reason’s task have toiled and wrought,
Quatrain no. 92
Alas — they milk a male cow, all for naught;
Better the cloak of foolishness be sought,
For today, none to reason gives a thought.
Since of truth and certainty our hands hold none,
Quatrain no. 177
we cannot sit in doubt and guesswork till life’s done;
take heed — let us not set the wine-cup from our hand:
in unknowing, sober man and drunken man are one.
These are not the verses of a man contradicting his treatises. They are the same verdict the treatises reach — that the method fails at its highest object — delivered without the obligation to be polite about colleagues. The consistency runs the other way from the usual account: the prose is guarded and the verse is candid, but they say the same thing.
Two cautions keep this from becoming too tidy. Khayyam never denies reason’s competence within its range; the quatrains that mock the philosophers sit alongside others in which reason is exactly what one is told to rely on — “Blame not the wheel of heavens — let reason be your ground” (no. 100). The target is overreach, not rationality, which is precisely Schopenhauer’s target too. And where Schopenhauer locates a third mode of consciousness in aesthetic contemplation, Khayyam points to something less exalted but structurally similar: a state between sobriety and drunkenness in which he says life itself is found (no. 212). Neither man is recommending stupefaction. Both are describing a mode of access that is neither inference nor its absence.
VIII. A Note on Transmission and Reception
There is no evidence that Schopenhauer read Khayyam, and this article claims none. The parallels are structural and independently arrived at, which is what makes them worth stating. But the usual formulation — that contact was impossible, that these were sealed worlds — is false in a way that illuminates both men.
Schopenhauer was the first major European philosopher to treat Eastern thought as philosophy rather than as ethnography. He said of the Upanishads that they had been the consolation of his life and would be the consolation of his death, and he read them for decades. What deserves notice is the route by which that text reached him. He knew it as the Oupnek’hat, Anquetil-Duperron’s Latin version of 1801–02 — and Anquetil-Duperron was translating not from Sanskrit but from the Persian Sirr-i Akbar, the rendering made by Dārā Shukōh in 1657. Schopenhauer’s most cherished book was Persian-mediated, and carried to him a vocabulary already inflected by Sufi and Neoplatonic usage that he could not read in the original and could not have separated out. The veil of Māyā, which does so much work in his system and which the quatrain above matches so closely, arrived in his hands through Persian.
The poetic channel was open as well. Joseph von Hammer-Purgstall’s Geschichte der schönen Redekünste Persiens, containing twenty-five quatrains of Khayyam in German, appeared in 1818 — the same year as the first volume of The World as Will and Representation — from a translator whose Persian work circulated widely in the German literary world Schopenhauer inhabited. Whether any of those pages crossed his desk is not established, and until someone works through his library records and marginalia it should not be asserted in either direction.
What can be said is how he would have received Khayyam, and the answer is unflattering to the tidiness of comparative philosophy. Schopenhauer judged religions by one criterion — whether they take the world to be fundamentally good or fundamentally not — and on that basis dismissed Islam as the poorest form of theism, too optimistic and too thin metaphysically to detain him. Presented with the Universals, he would have found the chain of order and filed its author among the optimists, without pausing over the chapter in which that author fails the philosophers, or the treatise in which he declines to endorse the proof at all. He would have rejected, as a representative of a tradition he had no use for, the one thinker in that tradition who observed his own restriction more faithfully than he did.
IX. Conclusion
The comparison yields a shape rather than a resemblance. Both philosophers hold that the demand for reasons is legitimate, exact, and bounded. Both mark the boundary instead of pretending it is not there. Both hold that whatever lies beyond it is not reached by argument, and both describe a non-inferential mode of access in its place. Both notice that causal explanation terminates in brute powers, and that familiarity disguises the termination. Both say that the veil, if lifted, takes the individual with it.
They divide at the last step, and the division is not the one the histories would predict. Schopenhauer, having proved that the principle of sufficient reason cannot carry us past experience, carries himself past it and names what he finds there. Khayyam, having laid out with complete competence the argument that would have taken him past it, sets the argument down, declines to give his opinion, and writes that after a lifetime of inquiry nothing became clear. One built a metaphysics on the far side of his own boundary. The other stayed on this side of it, and wrote quatrains about the weather here.
It is the older man who is the stricter critic of reason, and the modern one who could not resist the crossing. That is the finding, and it reverses the expected order of the two traditions.
References
Khayyam, ʿUmar. Risāla dar ʿIlm Kulliyāt-e Wujūd (A Treatise on the Science of the Universals of Being), in Dāneshnāme-ye Khayyāmī, pp. 381–390.
Khayyam, ʿUmar. Risāla fī al-Kawn wa al-Taklīf (On the World and Duty) — for the withholding of assent following the exposition of the philosophers’ proofs.
Khayyam, ʿUmar. Ḍarūrat al-Taḍādd fī al-Wujūd wa’l-Jabr wa’l-Baqāʾ (On the Necessity of Contradiction in the World, Determinism, and Subsistence).
Homaei, Jalāl al-Dīn, ed. Tarabkhaneh. Quatrain translations by Kam Austine.
Schopenhauer, Arthur. On the Fourfold Root of the Principle of Sufficient Reason (1813; revised 1847).
Schopenhauer, Arthur. The World as Will and Representation, vols. I (1818) and II (1844).
Schopenhauer, Arthur. Parerga and Paralipomena (1851), on religion and on the Upanishads.
Anquetil-Duperron, Abraham Hyacinthe. Oupnek’hat. Strasbourg, 1801–02 — Latin from the Persian Sirr-i Akbar of Dārā Shukōh (1657).
Hammer-Purgstall, Joseph von. Geschichte der schönen Redekünste Persiens, mit einer Blüthenlese aus zweyhundert persischen Dichtern. Vienna, 1818.
App, Urs. “Schopenhauer’s Favorite Book,” on the Oupnek’hat and its Persian and Sufi mediation.
See also: Gradation of Nobility, on the withholding of judgment in Risāla fī al-Kawn wa al-Taklīf; and Nihilism in Khayyam’s Philosophy: A Pre-Modern Encounter with the Void, which treats the pessimistic parallel with Schopenhauer, Nietzsche, and Camus.
Published as part of the Khayyam’s Philosophy Series — The Omar Khayyam Project
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