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Philosophy of Substance versus Philosophy of Nothingness


Milindapañha tells that King Milinda, an Indo-Greek king, talked with Nāgasena, a Buddhist sage, embraced the Buddhist faith and abandoned the household life to attain to Arahatship. The book is known to insist that the Buddhist philosophy of nothingness should be superior to the Western philosophy of substances, but actually Nāgasena’s theory was not so sophisticated as the Greek philosophy at that time. King Milinda did not abandon the household life and it is not certain whether he really understood Buddhism. Still he and his successors protected Buddhism, possibly because propagation of Buddhism could contribute to the stable reign.

Image by Richard Mcall + Henry Wang from Pixabay modified by me
A mighty statue of Alexander the Great versus a charitable statue of Buddha.

1. Does this text record historical facts?

Milindapañha (The Questions of King Milinda) is a Buddhist text supposedly documenting a dialogue between an Indo-Greek king named Milinda (Menander I Soter; 165/155 BC – 130 BC) and a Buddhist sage named Nāgasena. The book is often cited as the female singular Milindapañhā or as the male singular Milindapañho, whose stem is Milindapañha. The original text might have been written in Sanskrit[1] or Gandhari[2] around 100 BC, but the oldest existing texts are the translations in Pāli and Chinese. For quotation it is a convention to refer to the page numbers of Vilhelm Trenckner’s Romanized edition in Pāli, Milindapañha & Milinda-ṭīkā, published in 1880.

We do not know for sure what the original text in Sanskrit or Gandhari was. The existing Pāli translation is much larger than the Chinese. So we can guess that a lot of touches were added when they were translated into Pāli. Two translations must have stemmed from the common text, which is, however, not necessarily the original text. The common part has two similar sentences suggesting the end of the dialogue at page 64 and 89, which indicates some confusion of editing. The first half that begins at page 25 and ends at page 89 deals with the sort of questions that an outsider was likely to ask, while the latter half that begins at page 90 deals with esoteric doctrine of Buddhism. Judging from the contents, we can say the first half is close to the original text, while the biographical introduction before page 25 and the latter half consist mostly of fabrication in later ages. Of course the first half is not free from modification, because some questions put by King Milinda are based on Buddhist doctrine.

So much for philological matter, let us examine whether the text records historical facts correctly. Fig. 2 is an imaginary depiction of the dialogue between King Milinda and Nāgasena drawn in the early 20th century. Was this exotic scene real in 140 BC?

King Milinda asks questions of Nāgasena.[3]

Ample numismatic evidence indicates that King Milinda was a real king of the Indo-Greek Kingdom. The Indo-Greek Kingdom was a Hellenistic kingdom divided from the Graeco-Bactrians and covering the northwest regions of the Indian subcontinent during the last two centuries BC. Fig. 3 shows the territory and campaigns of the Indo-Greek Kingdom.

Indo-Greek territory and campaigns.[4]

Nāgasena, however, might be a fictitious name, because the name has a symbolic meaning “Army of Dragons" and we find his name nowhere but The Questions of King Milinda. Judging from his thought and his period, we can safely assume the Buddhist corresponding to Nāgasena was one of pioneers of the Sarvāstivāda (Pāli: sabbatthivāda), an early school of Buddhism.

Is it true that King Milinda embraced the Buddhist faith, as The Questions of King Milinda describes? This is the main theme of this article, but let me first focus on archaeological evidence. King Milinda left behind an immense corpus of silver and bronze coins, most of which shows he believed in Greek Gods.

Silver drachm of King Milinda (left) and Athena with thunderbolt and shield (right).[5]

But some bear designs of the eight-spoked wheel, the symbol of Buddhism.

Bronze coin of King Milinda with a Buddhist eight-spoked wheel (left) and the Greek symbols of victory, palm of victor (right).[6]

A Buddhist reliquary found in Bajaur bears a dedicatory inscription referring possibly to King Milinda. Morals by Plutarch (Greek: Πλούταρχος; Latin: Lucius Mestrius Plutarchus; c. 46 – 120 AD) tells that his death was treated like that of Gautama Siddhārtha (Pāli: Gotama Siddhattha), the founder of Buddhism.

When a certain man named Menander, who had been a good king of the Bactrians, died in camp, the cities celebrated his funeral as usual in other respects, but in respect to his remains they put forth rival claims and only with difficulty came to terms, agreeing that they should divide and carry away the ashes equally and should erect monuments to him in all their cities.[7]

This episode, however, only indicates that King Milinda was popular and does not prove he really believed in Buddhism. The Indo-Greek kingdom broke up after his death, but numismatic evidence suggests the succeeding Greek rulers also protected Buddhism. So, it is certain that King Milinda, though he originally believed in Greek Gods, engaged in a dialogue with one or more Buddhists and decided to protect Buddhism. Archaeological evidence, however, does not elucidate how deeply he understood Buddhism. Now we should read The Questions of King Milinda to recognize whether Nāgasena’s answer was convincing enough to convert Greek intellectuals to Buddhism.

2. Do names have no corresponding substances?

The first topic of the dialogue between King Milinda and Nāgasena was whether the name “Nāgasena" has any corresponding substance. Nāgasena’s assertion that “there is no permanent individuality[8]" surprised King Milinda. He said just as the object of the name “chariot" is neither any part of a chariot nor a mere aggregate of the parts, that is to say, nothing, a name is an empty sound referring to appearances caused by parts. Thus the dialogue started as the Greek philosophy of substances and the Buddhist philosophy of nothingness. King Milinda had anything – power, wealth and honor, while Nāgasena had nothing except the philosophy of nothingness. The difference of the two symbolizes the confrontation.

Nāgasena cited Vajira’s simile in Samyutta Nikaya, “Just as it is by the condition precedent of the co-existence of its various parts that the word 'chariot’ is used, just so is it that when the Skandhas are there we talk of a 'being’ [9]." The Skandhas (Pāli: khandhas) are the five functions that Buddhists think constitute the human being, namely matter (Sanskrit, Pāli: rūpa), sensation (Sanskrit, Pāli: vedanā), perception (Sanskrit: samjñā; Pāli: saññā), volition (Pāli: saṅkhāra; Sanskrit: samskāra) and discernment (Pāli: viññāṇa; Sanskrit: vijñāna). As King Milinda presupposed the Buddhist concept of Skandhas and Nāgasena used the same simile, the first dialogue would be a fiction or a modification based on Samyutta Nikaya. The topic of this book is a dialogue between Buddhists and Devil. So, the Greek philosophy of substances must have seemed to be Devil’s thought for Buddhists.

Before explaining why Buddhists regarded it as Devil’s thought to suppose a substance as the referral of a name, let me first examine whether Nāgasena’s nominalism is valid. Now chariot is a horse-drawn two-wheeled vehicle and the essence of wheeled vehicle in general is to minimize friction with earth according to the principle of a circle touching a line at a point. So long as it performs this function, any part of a chariot can be exchangeable and in this sense no part represents its essence. When a chariot is broken up into pieces, it ceases to be a chariot, even if it is the same as before in respect of materials. So, the mere aggregate of parts is not a chariot. But it does not follow that the referral of the name “chariot" has no persistence of a substance.

If what really exists is not a chariot but its parts, it will be led into regressus ad infinitum: what really exists is not the part but its parts and so on. The sarvāstivāda advocated the doctrine of atoms (Sanskrit: parama-aṇu)[10] and Nāgasena seems to have presupposed a similar doctrine. If what we call “chariot" were a mere aggregate of atoms, why could we have an idea of chariot? To it Nāgasena applied the Buddhist doctrine of dependent origination (Pāli:paticcasamuppāda; Sanskrit: pratītyasamutpāda). It has a broader and more ambiguous meaning than the relation of cause and effect in Western Philosophy, but here we can give a materialistic interpretation. That is to say, what really exists is not a chariot but its materialistic parts which cause sensation to produce the illusion of “chariot." The Sarvāstivāda has such a tendency to atomistic materialism.

Most of ancient Greek philosophers were idealistic. Plato’s idealism is a typical case. But some philosophers were materialistic and the most famous materialist was Epicurus (Greek: Ἐπίκουρος; 341 BCE – 270 BCE). He succeeded to the atomism of Democritus, denied the authority of traditional religion from the materialistic worldview and drew disciples ignoring traditional discrimination, as Gautama Siddhārtha did. You might think that Epicureanism was hedonism, while Buddhism was asceticism, but the difference is actually very small. Epicurus thought an attempt to satisfy desire leads rather to pain and its abandonment brings about the peace of mind (ἀταραξία) and the absence of pain (ἀπονία). At this point Epicureanism is metaphysically and ethically similar to Buddhism preaching that the renouncement of worldly desires leads to emancipation from pain.

Is the atomistic materialism true from the contemporary viewpoint? Even today some believe it to be scientifically true that what physically exists is only material or energy and the form to which we give a name is an illusion that our brains produce and has no physical reality, but this materialism is not physically true. The form of material is the lowness of entropy and has as much physical reality as material or energy. Of course we often mistake a form for another and in that case we must say it is a subjective illusion, but recognition of material and energy is not free from such a mistake either. Therefore we cannot say a form is more subjective than material and energy.

To make a systemical criticism of the ethics of Epicureanism and Buddhism, pain a living system has is the negative feedback warning the risk of an increase in entropy in it and in order to remove pain it must reduce the entropy, that is to say, maintain the form of the system. So, it is absurd to think of the form as an illusion to remove pain.

Is such a critique from the contemporary viewpoint inappropriate? Then, let us examine whether the ancient Greek philosophy can refute Ngasena or not. The Questions of King Milinda tells King Milinda praised Nāgasena’s reply, but if he had known Aristotle’s philosophy, he would have refuted Nāgasena’s nominalism, distinguishing substances and their qualities. According to Aristotle’s Metaphysics, a substance (ὑποκείμενον) is “the ultimate subject, which cannot be further predicated of something else [11]" and quality (ποιὸν) is “all affections of substance in motion in respect of which bodies become different when the affections change—e.g. heat and cold, whiteness and blackness, heaviness and lightness, etc.[12]" The substance is to its quality what the subject is to its predicate. If the quality is not essential to the substance, it is called accident (συμβεβηκὸς). A chariot preserves its identity as a substance, however much it may change its accidental qualities.

Aristotle says, the term “substance" has two meaning and it sometimes mean the form that is applied as a predicate rather than a subject[13]. This confusion should be attributed to Aristotle’s adherence to the grammatical structure of subject and predicate. Unlike Aristotelian logic, Fregean logic transforms the relation of subject and predicate into that of function and variable. To give a mathematical example, in Pythagorean Theorem x2+y2=z2 what value should be put in x or y is accidental and the essence of the right triangle persists as a substance regardless of the valuables. Wataru Hiromatsu (Japanese: 廣松渉; 1933-1994) said the Buddhist philosophy of nothingness is superior to the Western philosophy of substances in that it adopts relational worldview[14], but “relation" is not the antonym of “substance". Hiromatsu’s thesis of the priority of relation (Japanese: 関係の第一次性) turns the relation into a substance and it does not result in the non-existence of a substance.

Humans have the same functional identity as a chariot. The referral of “Nāgasena" sustains the personal identity for a life although metabolism exchanges the entire material that makes up his body after a certain period of time. Even if we admit the Buddhist doctrine that we are composed of the five Skandhas, we should not deny the existence of personal identity as the function unifying the five Skandhas. A substance need not persist for ever. We can find no substances in the absolute sense except energy. What I call substance here is a relatively invariable structure of a system in opposition to relatively variable elements. Both a chariot and Nāgasena are substances in this relative sense. Next we will focus on an attribute the latter has and the former does not.

3. Does the soul exist?

Ancient Indian and ancient Greek had a similar thought on the soul. The ancient Greek called the soul “psyche (Ψυχή)", which originally meant “breath". The ancient Indian called the soul “Ātman" in Sanskrit, which also originally meant “breath". In the Vedanta school of Hinduism, Ātman is the true self that is identical with the transcendent self, Brahman.

Associating the soul with breath is not systemically inappropriate, since a living system reduces its entropy by means of energy produced by breathing. But, of course the soul is the subject of breathing and not the breath itself. Antiochos, a court official of King Milinda, identified Nāgasena with “the soul, the inner breath which comes and goes[15]" and Nāgasena rightly proved it to be wrong.

King Milinda identified the soul (the living principle) with the subject of sensation, as is known from the following.

The living principle in the body which sees forms through the eye, hears sounds through the ear, experiences tastes through the tongue, smells odours through the nose, feels touch through the body, and discerns conditions through the mind–just as we, sitting here in the palace, can look out of any window out of which we wish to look, the east window or the west, or the north or the south.[16]

It is unnatural for the Greek to presuppose the Buddhist doctrine of six sense-bases (Sanskrit: Ṣaḍāyatana; Pāli: Saḷāyatana), eye, ear, nose, tongue, body and mind. Still it is not a pure fiction by Buddhists, because we cannot find the phrase “living principle (abbhantare jivo)" in other Pāli Buddhist texts. It seems to be an idea specific to King Milinda.

Nāgasena replied to King Milinda as follows.

Now, as we are seated here in the palace, we see all kinds of objects plainly in full daylight with these windows all thrown open, if we only stretch forth our heads. Can the living principle do the same when the doors of the eyes are thrown open? When the doors of the ear are thrown open, can it do so? Can it then not only hear sounds, but see sights, experience tastes, smell odours, feel touch, and discern conditions? And so with each of its windows? [17]

Suppose a dwarf in a person is in charge of sensation. Then you must suppose further a dwarf in the dwarf and the supposition will be led into regressus ad infinitum. The soul is not a substance inside the body in this meaning just as the essence of a chariot is not a substance hidden inside the chariot.

Setting aside a Greek layman, Greek philosophers, at least, did not give such a naïve interpretation to the soul. Aristotle’s De Anima (On the Soul), for example, attributed the relation of soul and body to that of form and material, actuality (ἐντελέχεια) and potentiality (δύναμις), substance and accident.

It follows, then, that the Vital Principle must be a substance, as being the form of a natural body holding life in potentiality; but a substance is a reality,—the actuality, that is, of a body such as has been described. And actuality is, in the twofold signification, either of knowledge or of reflexion.[18]

Form and material are not separable but conceptually distinguishable. Therefore Aristotle did not think that the soul in the body is a dwarf. As he recognized, the soul is an information system whose activities are not separable but conceptually distinguishable from material.

Though the doctrine of non-Self (Sanskrit: anātman; Pāli: anattā) is one of the three marks of Buddhism (Sanskrit: trilakṣaṇa; Pāli: tilakkhaṇa), Gautama’s original preachment was not a metaphysical one: “There is no Self," but an ethical one: “Throw away your attachment for yourself." He did not answer a metaphysical question like whether the soul continues after death or not. He left metaphysical questions “unexplained (Sanskrit: avyākṛta; Pāli: avyākata)", because the debate about them brings about an attachment for a specific theoretical position and disturb mind.

Why then did the doctrines of non-Self and impermanence (Sanskrit: anitya; Pāli: anicca) become the three marks of Buddhism? If it were not for Self, one cannot be attached to one’s Self. The desire to throw away the attachment to Self seems to have led to the assumption that there would be no Self. In the same way, the desire to throw away the attachment to wealth, power and so on seems to have led to the assumption that they would be impermanent. Buddhists in Samyutta Nikaya regarded the negation of non-Self as Devil’s thought, because they thought it awoke the attachment for Self and eventually caused an inescapable pain.

This sort of assumption is specific to Buddhism. For example, Buddhists think that women defile men. Male Buddhists wish that women were detestable enough for them to throw away the attachment to the women and this wish has been transformed into the sexist prejudice so as to make the detachment eternal.

We can also explain by the same law why many people have written Buddhist scriptures under the disguise of Gautama. The desire to become a Gautama must have developed into the assumption that the author would be Gautama. Another explanation is that the Buddhist doctrine of non-Self made the distinction between the authors and Gautama unnecessary.

4. Does Saṃsāra contradict non-Self ?

The Indian have long believed Saṃsāra (Sanskrit, Pāli), the repeating cycle of death and reincarnation of living things according as their karma (Pāli: kamma; Sanskrit: kárman). Buddhism also succeeded this doctrine and preaches about karmic retribution. The ancient Greek people except the Pythagoreans, Plato and so on did not believe in Saṃsāra and King Milinda asked many questions about it, because Saṃsāra seemed contradictory to non-Self and the negation of persistent identity of the soul seemed to make the karmic retribution ethically meaningless.

According to Nāgasena, the subject of Saṃsāra is name-and-matter (Pāli, Sanskrit: Nāmarūpa), of which matter (rūpa) corresponds to the first Skandha, the physical properties of being and name (nāma) corresponds to the other four Skandhas, the spiritual properties of being. Though this dichotomy of name/matter is similar to Aristotle’s distinction between form/material, the former is different from the latter in that name-and-matter has no persistent identity as a substance. Nāgasena used the following simile to explain that name-and-matter of this life and that of the future life are different but combined through the dependent origination.

Nāgasena 'It is like milk, which when once taken from the cow, turns, after a lapse of time, first to curds, and then from curds to butter, and then from butter to ghee. Now would it be right to say that the milk was the same thing as the curds, or the butter, or the ghee?’

King Milinda 'Certainly not; but they are produced out of it.’

Nāgasena 'Just so, O king, is the continuity of a person or thing maintained. One comes into being, another passes away; and the rebirth is, as it were, simultaneous. Thus neither as the same nor as another does a man go on to the last phase of his self-consciousness.’[19]

Curds, butter, and ghee are the products of the lactic acid fermentation. It changes the molecular formation of milk but its material remains the same. You might think that as an elemental particle has no identity Buddhism is right in that material has no continuity at the micro level of quantum physics, but this contemporary interpretation cannot be applied to the current example at the macro level.

According to Nāgasena the newly born name-and-matter cannot be released from its evil karma even if there is discontinuity between the new and the old, just as the contract of buying a vessel of milk remains valid even if it becomes curds.[20] Is his conclusion persuasive that the no-Self does not contradict Saṃsāra or karmic retribution? If the new name-and-matter is just causally related to and not as a substance identical to the old one that committed the evil karma, the new one should be cleared of the charge. If it must be charged with it, the two should have the personal identity as the subject of responsibility.

The biggest reason Nāgasena’s excuse is not persuasive consists in his substitution of the metaphysical doctrine “there is no Self" for the ethical one “throw away your attachment to your Self." It is because you are attached to your Self that you are involved in Saṃsāra with your Self. If you are detached from your Self, you can be emancipated from the ties of the earth. Nāgasena denied the existence of Self so as not to be attached to it. As a consequence it becomes unclear why the non-existent Self can be involved in Saṃsāra and why the emancipation is necessary to be released from its evil karma.

5. Why did King Milinda protect Buddhism?

The Questions of King Milinda tells that King Milinda was convinced of all answers by Nāgasena and praised him. “Afterwards, taking delight in the wisdom of the Elder, King Milinda handed over his kingdom to his son, and abandoning the household life for the houseless state, grew great in insight, and himself attained to Arahatship.[21]" Is it a historical fact? Though Nāgasena admitted that both a layman and a recluse can attain to Arahatship, he said,

But nevertheless, O king, it is the recluse who is the lord and master of the fruit of renunciation. And renunciation of the world, O king, is full of gain, many and immeasurable are its advantages, its profit can no man calculate.[22]

King Milinda answered to it, “Very good, Nâgasena! That is so, and I accept it as you say." So, it would be inconsistent, if he had not abandoned the household life. But there is no other evidence that supports this story. Plutarch tells that he died at a military camp (στρατόπεδον), that is to say, he continued to reign until his death. This must be the fact.

Taking the Buddhists’ tendency to turn their wish to reality into consideration, we must doubt whether King Milinda was really convinced of all answers by Nāgasena or not. When you read The Questions of King Milinda, you will notice such a labored case where King Milinda fully agreed with Nāgasena’s doctrine of non-Self and then put another question doubting it. In a real dialogue King Milinda, unconvinced of some questions by Nāgasena, would have put various questions from every angle, since, as we have seen, a man with the knowledge of Greek philosophy could have refuted Nāgasena.

Of course I am ready to admit King Milinda and his followers protected Buddhism. But as is evident from the fact that he did not renounce the world, he did not believe in Buddhism with all his heart. Probably he would rather utilize it politically. Since the Indian caste system shunned the foreign rulers including the Greek as outcastes or untouchables, they welcomed, protected and propagated Buddhism which, unlike the traditional Indian religions, denied the caste system.

Protecting and propagating Buddhism gave other advantages not only to foreign rulers but also to domestic rulers. The Indian caste system ranks Brahmin (priests) first, Kshatriyas (warriors) second, Vaishyas (traders) third and Shudras (workmen) fourth. Kshatriyas and Vaishyas were dissatisfied with the system, because they were subordinate to Brahmin in spite of their power and wealth. So, they protected Buddhism to restrain the Brahmin’s arrogance.

It is very important for rulers with power and wealth to prevent the powerless and the poor from rebelling against them. It is because they are attached to power and wealth that the powerless and the poor try rebellion. If the rulers propagate Buddhism among the powerless and the poor, they will become likely to throw away the attachment to power and wealth and unlikely to attempt rebellion.

Thanks to the protection by Kshatriyas and Vaishyas, Buddhism could flourish in a secular sense. But it was paradoxical for the religion that persuaded people out of power and wealth to be attached to those with power and wealth. The hypocritical ideology for rule lost popularity and instead the indigenous religion, Hinduism, attained popularity. When the Islamic gained power, Buddhists lost their patrons and Buddhism disappeared from India, Pakistan and Afghanistan.

6. References

  1. Paul Pelliot. “Les Noms propres dans les traductions chinoises du Milindapañha." Journal Asiatique. Série 11, Tome 4, 1914. p. 390-400.
  2. Oskar von Hinüber. A Handbook of Pali Literature, Indian Philology and South Asian Studies, 2. de Gruyter (June 1, 2002). p. 83.
  3. Hutchinson’s story of the nations. Nabu Press (October 9, 2010).
  4. Wikimedia Commons. “Territorial map of the Indo-Greeks, according to the “Atlas der Welt Geschichte." Self-made, 2007." Licensed under CC-BY-SA.
  5. Silver bilingual tetradrachm of Menander I (155-130 BCE). Obverse: Greek legend, ΒΑΣΙΛΕΩΣ ΣΩΤΗΡΟΣ ΜΕΝΑΝΔΡΟΥ (BASILEOS SOTEROS MENANDROU), literally, “Of Saviour King Menander." Reverse: Kharosthi legend: MAHARAJA TRATARASA MENADRASA “Saviour King Menander." Athena advancing right, with thunderbolt and shield. Taxila mint mark." Licensed under CC-0.
  6. Menander Chakra." Licensed under CC-0.
  7. “Μενάνδρου δέ τινος ἐν Βάκτροις ἐπιεικῶς βασιλεύσαντος εἶτ´ ἀποθανόντος ἐπὶ στρατοπέδου, τὴν μὲν ἄλλην ἐποιήσαντο κηδείαν κατὰ τὸ κοινὸν αἱ πόλεις, περὶ δὲ τῶν λειψάνων αὐτοῦ καταστάντες εἰς ἀγῶνα μόλις συνέβησαν, ὥστε νειμάμενοι μέρος ἴσον τῆς τέφρας ἀπελθεῖν, καὶ γενέσθαι μνημεῖα παρὰ πᾶσι τοῦ ἀνδρός." Πλούταρχος. “Ἠθικά, Πολιτικὰ παραγγέλματα." p. 821e. Translation: Plutarch (Author), Frank Cole Babbitt (Translator). Plutarch: Moralia, Volume IV, Roman Questions. Greek Questions. Greek and Roman Parallel Stories. On the Fortune of the Romans. On the Fortune or the … in Wisdom? Precepts of Statecraft. 28.
  8. “Na hettha puggalo upalabbhati" Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 25.
  9. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 27.
  10. Abhidharma Mahāvibhāṣa Śāstra. Translation: 玄奘 (translator). 『阿毘達磨大毘婆沙論』Kindleアーカイブ (April 16, 1947). 巻127.
  11. “τό θ᾽ ὑποκείμενον ἔσχατον, ὃ μηκέτι κατ᾽ ἄλλου λέγεται." Αριστοτέλης. Μεταφυσικά.Βιβλίο Δ, 1017b. Translation: Aristotle (Author), C. D. C. Reeve (Translator). Metaphysics. Hackett Publishing Company, Inc.; UK ed. edition (March 1, 2016).
  12. “ἔτι ὅσα πάθη τῶν κινουμένων οὐσιῶν, οἷον θερμότης καὶ ψυχρότης, καὶ λευκότης καὶ μελανία, καὶ βαρύτης καὶ κουφότης, καὶ ὅσα τοιαῦτα, καθ᾽ ἃ λέγονται καὶ ἀλλοιοῦσθαι τὰ σώματα μεταβαλλόντων." Αριστοτέλης. Μεταφυσικά.Βιβλίο Δ, 1020b. Translation: Aristotle (Author), C. D. C. Reeve (Translator). Metaphysics. Hackett Publishing Company, Inc.; UK ed. edition (March 1, 2016).
  13. Αριστοτέλης. Μεταφυσικά.Μεταφυσικά, Βιβλίο Δ, 1017b. Translation: Aristotle (Author), C. D. C. Reeve (Translator). Metaphysics. Hackett Publishing Company, Inc.; UK ed. edition (March 1, 2016).
  14. 廣松渉, 吉田宏晢. 『仏教と事的世界観』朝日出版社 (December 1, 1979). p. 36-52.
  15. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 30.
  16. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 54.
  17. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 55.. A similar debate is repeated at page 86-87
  18. “ἐπεὶ δ’ ἐστὶ καὶ σῶμα καὶ τοιόνδε, ζωὴν γὰρ ἔχον, οὐκ ἂν εἴη σῶμα ἡ ψυχή; οὐ γάρ ἐστι τῶν καθ’ ὑποκειμένου τὸ σῶμα, μᾶλλον δ’ ὡς ὑποκείμενον καὶ ὕλη. ἀναγκαῖον ἄρα τὴν ψυχὴν οὐσίαν εἶναι ὡς εἶδος σώματος φυσικοῦ δυνάμει ζωὴν ἔχοντος. ἡ δ’ οὐσία ἐντελέχεια; τοιούτου ἄρα σώματος ἐντελέχεια. αὕτη δὲ λέγεται διχῶς, ἡ μὲν ὡς ἐπιστήμη, ἡ δ’ ὡς τὸ θεωρεῖν." Αριστοτέλης. Περί ψυχής.Βιβλίο Β, Κεφάλαιο 1. p. 412. a20. Tranlation: Aristotle (Author), Hugh Lawson-Tancred (Translator). De Anima (On the Soul). Penguin; Reissue edition (July 29, 2004).
  19. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 40-41.
  20. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 48.
  21. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 419.
  22. Vilhelm Trenckner, Padmanabh S. Jaini, et al. (editor). Milindapañha & Milinda-ṭīkā. Pali Text Society (December 1, 1986). p. 243.