One of Plutarch’s main concerns with the Platonists of his time regards their misunderstanding of Plato’s dualism. By identifying the opposition between a good and an evil principle with that between the intelligible and matter, they end up in a position very similar to that of the Stoics, who introduce evil without proper explanation. While the Stoics are compelled to trace evil back to god’s causality, explaining it as a necessary by-product,Footnote 1 these Platonists argue that something formless and unqualified, like matter, can adequately account for evil. But such a weak account of evil was certainly not what Plato had in mind, according to Plutarch. The evil we see at work in the cosmos cannot be simply explained by matter’s ontological deficiencies. Plato was careful to propose a proper principle of evil: an irrational soul, coeval with both matter and god. This soul, Plutarch argues, is the principle Plato refers to as necessity in the Timaeus. Therefore, necessity in the Timaeus should not be identified with matter, but with this third psychic principle.
[T1] οἱ δὲ τὴν ἐν Τιμαίῳ λεγομένην ἀνάγκην … τῇ ὕλῃ προστιθέντες ἀλλὰ μὴ τῇ ψυχῇ, ποῦ θήσονται τὸ τὴν ὕλην ἀεὶ μὲν ἄμορφον καὶ ἀσχημάτιστον ὑπ’ αὐτοῦ λέγεσθαι καὶ πάσης ποιότητος καὶ δυνάμεως οἰκείας ἔρημον, εἰκάζεσθαι δ’ ἀώδεσιν ἐλαίοις, ἃ πρὸς τὰς βαφὰς οἱ μυρεψοὶ λαμβάνουσιν; οὐ γὰρ οἷόν τε τὸ ἄποιον καὶ ἀργὸν ἐξ αὑτοῦ καὶ ἀρρεπὲς αἰτίαν κακοῦ καὶ ἀρχὴν ὑποτίθεσθαι τὸν Πλάτωνα καὶ καλεῖν ἀπειρίαν αἰσχρὰν καὶ κακοποιόν, αὖθις δ’ ἀνάγκην πολλὰ τῷ θεῷ δυσμαχοῦσαν καὶ ἀφηνιάζουσαν. ἡ γάρ “ἀναστρέφουσα” τὸν οὐρανόν, ὥσπερ ἐν Πολιτικῷ λέγεται, καὶ ἀνελίττουσα πρὸς τοὐναντίον ἀνάγκη καὶ “σύμφυτος ἐπιθυμία” … πόθεν ἐγγέγονε τοῖς πράγμασιν, εἰ τὸ μὲν ὑποκείμενον ἄποιος ἦν ὕλη καὶ ἄμοιρος αἰτίας ἁπάσης, ὁ δὲ δημιουργὸς ἀγαθὸς … τρίτον δὲ παρὰ ταῦτα μηδέν; αἱ γὰρ Στωικαὶ καταλαμβάνουσιν ἡμᾶς ἀπορίαι, τὸ κακὸν ἐκ τοῦ μὴ ὄντος ἀναιτίως καὶ ἀγενήτως ἐπεισάγοντας· ἐπεὶ τῶν γ’ ὄντων οὔτε τὸ ἀγαθὸν οὔτε τὸ ἄποιον εἰκός ἐστιν οὐσίαν κακοῦ καὶ γένεσιν παρασχεῖν. ἀλλὰ ταὐτὸ Πλάτων οὐκ ἔπαθε τοῖς ὕστερον, οὐδὲ παριδὼν ὡς ἐκεῖνοι τὴν μεταξὺ τῆς ὕλης καὶ τοῦ θεοῦ τρίτην ἀρχὴν καὶ δύναμιν ὑπέμεινε τῶν λόγων τὸν ἀτοπώτατον, ἐπεισόδιον οὐκ οἶδ’ ὅπως ποιοῦντα τὴν τῶν κακῶν φύσιν ἀπ’ αὐτομάτου κατὰ συμβεβηκός. (An. procr. 1014F–15B)
Those, however, who attribute to matter and not to the soul what in the Timaeus is called necessity … what will they make of the fact that by Plato matter is said always to be amorphous and shapeless and devoid of all quality and potency of its own and is likened to odourless oils which makers of perfume take for their infusions? For what is without quality and of itself inert and without propensity Plato cannot suppose to be the cause and principle of evil and call ugly and maleficent infinitude and again necessity which is largely recalcitrant and refractory to god. In fact, the necessity and ‘congenital desire’ whereby the heaven is reversed, as is said in the Politicus, and rolled back in the opposite direction … whence did this come to be in things if the substrate was unqualified and the artificer good … and third besides these there was nothing? For we are involved in the same difficulties of the Stoics by bringing in evil without cause and process of generation out of what is non-existent, since of things that do exist neither what is good nor what is without quality is likely to have occasioned evil’s being or coming to be. The same thing did not happen to Plato, however, as did to those who came later, for he did not as they did by overlooking the third principle and potency, which is intermediate between matter and god, acquiesce in the most absurd of doctrines that make the nature of evil supervenient. (transl. Cherniss, slightly modified).
Plato introduces necessity at Timaeus 47e3–5, which appears to mark a fresh start—and, indeed, it is often regarded as the beginning of the ‘second part’ of the dialogue, concerning the works of necessity and dealing with the receptacle.Footnote 2 This passage was of particular importance for Platonists before Plutarch, as it offered a privileged perspective on the nature and number of the principles posited by Plato. Ps.-Timaeus Locrus’ On the Nature of the Cosmos provides valuable evidence of this kind of approach, as the treatise begins by opposing two kinds of causes, namely the forms and necessity, with reference to Timaeus 47e3–5, and identifies necessity with the receptacle, describing it as both disordered and unqualified. The same operation was carried out by other Platonists of that time, as we can see from Eudorus’ fragments and pseudo-Archytas’ On Principles, which postulate a couple of principles, the intelligible as the principle of good things and matter as the principle of evil things.Footnote 3
This is the kind of approach criticized by Plutarch in [T1]: Plato described the receptacle as receptive and unqualified (for example at Ti. 50b6–51b1), while necessity is portrayed as needing to be persuaded by the god.Footnote 4 According to Plutarch, when Plato speaks of a pre-cosmic ἀταξία (Ti. 30a5), he is clearly referring to a principle that moves disorderly, not to the unqualified receptacle.Footnote 5 However, although Plutarch can cite passages in Plato’s corpus that refer to an irrational soul (though only a few, to be honest), the question arises of how he could find this a plausible reading of the second part of the Timaeus and claim that in this section three principles, rather than two, are at play. In other words, how could he claim that necessity and the receptacle refer to two different principles in this section of the Timaeus? In what follows, I argue that a passage of the De Iside provides the answer to this puzzle: Plutarch reads the sentence μεικτέον καὶ τὸ τῆς πλανωμένης εἶδος αἰτίας, ᾗ φέρειν πέφυκεν at 48a6–7 to mean that, besides god and necessity, a third kind of cause must be considered, namely the receptacle or wandering cause.
At De Iside 371A–B, one of the key passages of the treatise, Plutarch clearly has Timaeus 47e3–48a7 in mind. This time it is not just a reference, but a quasi-quotation of the passage:

Plutarch’s words closely recall the Timaeus: our cosmos has been mixed out of two opposing principles (here, Osiris and Typhon); while the good and intelligible power prevails over its opponent, this latter cannot be completely mastered (Plato’s τὰ πλεῖστα—most things, but not all—is emphasized in Plutarch’s text). As mentioned, the other Platonists believed that this passage of the Timaeus concerned two principles, namely nous and necessity. However, the De Iside, presents a triad, and not a couple, of principles: Isis, Osiris and Typhon.
The identity of these characters is debated among scholars—except for Osiris, whom almost all agree to identify with the intelligible realm (god and the forms).Footnote 6 However, beyond interpretative divergences, what emerges clearly from the text is that Isis is a receptive nature, while Typhon embodies a subversive and irrational power. [T2] refers to the opposition between Osiris and Typhon—which, by closely echoing Timaeus 47e3–48a7, Plutarch maps onto the opposition between nous and necessity, identifying Osiris with the former and Typhon with the latter. This aligns perfectly with Plutarch’s description of Typhon in the De Iside, as he is portrayed through terms that in the De animae procreatione are used to describe the irrational soul, or necessity.Footnote 7
Plutarch argues that to these two characters, a third entity must be added—one that allows the encounter of the two opposing powers, the good and the evil ones, serving as a neutral and receptive battlefield.Footnote 8 Without this third nature the two powers could not interact. This principle, Isis, is described as a receptive nature, with a terminology that closely echoes Timaeus 49a6 (πάσης εἶναι γενέσεως ὑποδοχὴν αὐτὴν οἷον τιθήνην) and 50b6–51b1, the passages on the receptacle. Plutarch claims that she is the principle that Plato called nurse and all-receiving (372E), serving as a substrate for the encounter of Osiris and Typhon.Footnote 9 This situation mirrors that described in [T1], where Plutarch distinguishes two principles besides the intelligible: the irrational soul, which he identifies with necessity, and the receptacle or matter.
Therefore, [T2] provides further evidence that Plutarch’s approach differs from that of the other Platonists, who interpreted the mention of necessity at Timaeus 47e3 and the description of the unqualified receptacle as mother and nurse at 50b6–51b1 as both referring to the same principle, namely matter. Indeed, the Platonists’ interpretation of the second part of the Timaeus appears as the most natural (cf. also below on [T3a]), prompting the questions of whether Plutarch’s reading is simply misleading. Arguing that in the second part of the Timaeus necessity and the receptacle refer to two different principles appears as a rather difficult task. However, a clue of how Plutarch intends to read this passage is provided by his identification of Isis with the wandering cause.Footnote 10 As it will turn out, although unusual, Plutarch’s reading of the text is not wrong. Let us return to the Timaean passage in question and analyse [T3] in its broader context:
[T3a] τὰ μὲν οὖν παρεληλυθότα τῶν εἰρημένων πλὴν βραχέων ἐπιδέδεικται τὰ διὰ νοῦ δεδημιουργημένα· δεῖ δὲ καὶ τὰ δι’ ἀνάγκης γιγνόμενα τῷ λόγῳ παραθέσθαι. μεμειγμένη γὰρ [48a] οὖν ἡ τοῦδε τοῦ κόσμου γένεσις ἐξ ἀνάγκης τε καὶ νοῦ συστάσεως ἐγεννήθη· νοῦ δὲ ἀνάγκης ἄρχοντος τῷ πείθειν αὐτὴν τῶν γιγνομένων τὰ πλεῖστα ἐπὶ τὸ βέλτιστον ἄγειν, ταύτῃ κατὰ ταῦτά τε δι’ ἀνάγκης ἡττωμένης ὑπὸ πειθοῦς ἔμφρονος οὕτω κατ’ ἀρχὰς συνίστατο τόδε τὸ πᾶν. εἴ τις οὖν ᾗ γέγονεν κατὰ ταῦτα ὄντως ἐρεῖ, μεικτέον καὶ τὸ τῆς πλανωμένης εἶδος αἰτίας, ᾗ φέρειν πέφυκεν. (Ti. 47e3–48a7)
With a few exceptions, what has been considered so far in the discussions has already shown things produced by art through intellect. However, it is necessary to place alongside them in our discourse those that have generation through necessity (δεῖ δὲ καὶ τὰ δι’ ἀνάγκης γιγνόμενα τῷ λόγῳ παραθέσθαι). For it is as a result of a mixture, stemming from the composition of necessity and intellect, that the generation of this cosmos was produced. Since intellect dominates necessity, persuading it to guide the majority of things with generation toward the good, the universe was originally composed in this way and according to these principles, through a necessity overcome by intelligent persuasion. Therefore, if one wishes to assert how it truly came into being under these conditions, it will be necessary to also consider the form of the wandering cause, which by nature has the ability to sustain (μεικτέον καὶ τὸ τῆς πλανωμένης εἶδος αἰτίας, ᾗ φέρειν πέφυκεν [my translation]).
All modern interpreters usually take necessity, the wandering cause and the receptacle to refer to one principle—just as the Platonists criticized by Plutarch in [T1]. The sentence μεικτέον καὶ τὸ τῆς πλανωμένης εἶδος αἰτίας, ᾗ φέρειν πέφυκεν is interpreted as repeating and rephrasing δεῖ δὲ καὶ τὰ δι’ ἀνάγκης γιγνόμενα τῷ λόγῳ παραθέσθαι. First, Plato states that besides intellect, necessity should be considered too, and then rephrases it by saying that besides intellect, we should add the genre of the wandering cause. Interestingly, although this sounds as the most natural reading of the passage, it raises no few interpretative problems.
(a) One problem concerns the meaning of ‘wandering cause’, as it is unclear what aspect this expression conveys and how the notion or erring and wandering could be reconciled with that of necessity.Footnote 11 (b) A further, more specific, problem concerns the translation of φέρειν in the quoted sentence: does it mean ‘to move’, with reference to the pre-cosmic disordered motions, or rather ‘to sustain’, with reference to the receptive nature of the receptacle?Footnote 12 (c) The most problematic issue, however, concerns Plato’s interpretation of the pre-cosmos—a problem that, as mentioned, did not escape Plutarch. At 30a3–6, Plato mentions a state of disorderly motion, and at 48a2–5, he claims that necessity needs to be persuaded by nous. However, at 50b6–51b1, he argues that the receptacle must be purely receptive and unqualified, in order to serve as a substrate for cosmic generation. These descriptions raise the question of whether Plato’s receptacle is akin to bare matter that artisans mould (certainly positing some limits, but not being disordered or recalcitrant), or whether this underlying substance is moving disorderly and needs to be persuaded, as the association with necessity suggests.Footnote 13 Beyond the brilliant interpretative solutions proposed by scholars, the impression remains that two different images are here at play.
This is not the only possible reading of [T3a], however. There is another way of reading the sentence μεικτέον καὶ τὸ τῆς πλανωμένης εἶδος αἰτίας, ᾗ φέρειν πέφυκεν, namely as pointing to a third cause—the reading that we find in Plutarch’s passage. According to this reading, this sentence would not mean that besides intellect we should also take into account necessity, rephrasing 47e3–5; rather, it would say that besides intellect and necessity one must add the wandering cause. The entire section of 47e3–48a7 would, thus, present a two-steps argument:Footnote 14 if the world really is a mixture of necessity and intellect, we must also take into account necessity besides intellect (47e3–5). But to these two, we must also add (μεικτέον καί) the third cause, namely the wandering cause, which sustains them (in Plutarch’s view, serving as a receptacle for their encounter or mixture).Footnote 15 It is this latter cause, not necessity, that Plato identified with the all-receiving receptacle mentioned at 50b6–51b1.
This reading not only avoids the repetition in the Timaean text (Plato has just stated that we should add necessity; why, after all, would he repeat it?) but it also solves the perennial problem of understanding how Plato characterizes the receptacle. In Plutarch’s reading, there is no tension in the description of the receptacle. This stems from his distinction between necessity and the receptacle as two different causes (as confirmed by his statement in [T1] that necessity and matter are two different principles), one moving disorderly and the other being unqualified and receptive. This solution also explains why ‘necessity’ and ‘wandering cause’ seem to refer to two different semantic fields—they simply refer to two different principles.
Αs mentioned at the outset, however, the real significance of Plutarch’s operation goes far beyond interpretative problems and addresses a deeper philosophical issue, one that he felt had been left unaddressed by both the Platonists and the other important schools like Stoicism. How can we explain the evil that is so pervasive in our everyday experience? While the Stoics did not address this problem, the Platonists identified the cause of evil with matter, due to its being lack and privation of form and order, and because they considered the body to be what leads our soul astray. Plutarch’s dissatisfaction with this answer is evident: privation and lack cannot explain evil; they only explain deficiency, much as our body does not account for vice. Only an irrational psychic entity can offer an adequate explanation of evil—and this, according to Plutarch, is what Plato did not fail to address. Overall, although it may seem misleading at first glance and is certainly not endorsed by any modern scholar, Plutarch’s reading is not grammatically incorrect and is motivated by both interpretative and philosophical concerns. The question remains open of whether Plato really addressed the question of evil as clearly as Plutarch believes, which highlights both the beauty and danger of philosophical exegesis.