What we have of his work as a commentator are his comments on the first and sixth book of the Nicomachean Ethics and his commentary on the second book of the Posterior Analytics, all of which are in the tradition of the large exegetical commentaries of Late Antiquity. It may be that in the case of the Nicomachean Ethics the reason why he chose to comment on these particular books was that the rest of Aristotle’s ethical treatise had been commented on or was commissioned to be commented on by Michael of Ephesos and other anonymous commentators. It is not clear, however, why Eustratios chose to comment only on the second book of the Posterior Analytics, especially since it seems that the whole of Alexander of Aphrodisias’ commentary was still accessible. The comments on the Nicomachean Ethics were translated in the thirteenth century by Robert Grosseteste and became very influential in the West through the agency of Albert the Great.
In interpreting Aristotle’s works, Eustratios followed the Neoplatonic philosophers, though at certain places he advocated theses, which slightly deviated from those of all ancient philosophers and tried to be more in close agreement with his Christian beliefs. For instance, concerning the issue of the knowledge of first principles, Eustratios’ view differs both from what Plato and the Platonists standardly held about the knowledge of the Ideas as well as from what Aristotle said about the understanding of first principles. Commenting on Posterior Analytics 2.19, Eustratios started his account in a clearly Neoplatonic manner, by claiming that, since in the hierarchy of beings the soul comes right after the intellect, it participates more than anything else in what the intellect grasps, and thus the common and self-evident notions, which it possesses are nothing but resonances of what the intellect grasps. But in what follows he did not defend the view that the human soul regains pieces of knowledge, which it possessed at some former time, nor that it has only potential knowledge, which then becomes actual. On the contrary, he argued that the human soul has full knowledge of the principles, the common, self-evident concepts, already when we are born, but that this knowledge is obscured by our bodily impulses. It is only when our soul is guided either by our sense perceptions or by appropriate teaching that the common and self-evident notions come forth, so that we, as it were, wake up and can immediately assent to the first principles. There should be no doubt that Eustratios is influenced here by Neoplatonic views, which he tried to integrate into his Christian outlook. For the human soul, according to Christian doctrine, when created by God, is created with all the knowledge it needs. If human beings lose sight of the knowledge and understanding that their soul possesses, it is only because they are susceptible to and overwhelmed by the impulses generated by their body. On the other hand, if human beings manage to purify themselves from the bodily passions, they can come to have knowledge of the ultimate truth.
Concerning the problem of universals, Eustratios, just like his teacher Italos and many other Byzantine philosophers, defended the Neoplatonists’ theory according to which universals exist in three modes; namely, they exist as universals ‘‘before the many (particulars)’’ in God’s mind, as universals ‘‘in the particulars” within perceptible individuals, and finally as universals ‘‘after the particulars’’ in the form of concepts acquired by our mind by abstraction of the common characteristics of perceptible individuals. Joannou, and more recently Lloyd, have presented Eustratios as following Italos in being a nominalist, that is, in adhering to the position that universals are mere names stripped of all reality and existing only in the human mind. However, on Giocarinis’ view Eustratios should not be regarded as a nominalist, since he follows the Platonic tradition, which treats the universals before the particulars as the thoughts of Intelligence, and thus they enjoy actual existence; as to the other types of universals, they are solely in intellectu as bare concepts or thoughts, which are not acquired by abstraction but the human mind possesses them right from the beginning. Finally, Benakis has labeled Eustratios’ position on universals conceptual or moderate realism, and stressed that it is not a nominalist position, since even the a posteriori status of the universals after the particulars does not alter the fact that they do exist.
In this context, Eustratios’ account of the distinction between gene and eide is pertinent. According to Eustratios, gene do not subsist (anupostata), whereas eide can be said to subsist; for since eide come right after the particulars while gene come after eide, gene are mere concepts or thoughts (ennoemata), and have only a faint resemblance to perceptible individuals, whereas eide, as soon as matter is added to them, actually subsist in perceptible individuals. In fact, Eustratios recognized three different senses of eidos: it can be understood either as a species, or as a form common to many perceptible individuals, or finally as the form in a specific individual. Hence, when Eustratios draws a distinction between gene and eide as having different ontological status, he thought of eide not as species, because eide as species are, just like gene, mere concepts or thoughts which do not subsist; he rather thought of an eidos understood either as a form common to many perceptible individuals or as the form in a specific individual, and it is in these two senses that eide are said to subsist insofar as they subsist in the perceptible individuals. Against Plato, therefore, he would object that eide do not have separate existence outside the divine mind, while against Aristotle he would object that gene and eide, understood as species, are not even secondary substances. In fact, Eustratios uses every chance to stress, in his commentaries as well as in his theological treatises, that God’s thoughts and the particulars are substances (hupostaseis) and exist per se, whereas what the human mind acquires by abstraction from the common characteristics ofperceptible individuals either merely subsists or does not even subsist.
See also: > Albert the Great > Epistemology, Byzantine
> John Italos > Logic, Byzantine > Michael of Ephesus
> Nicomachean Ethics, Commentaries on Aristotle’s
> Robert Grosseteste > Syllogism, Theories of
> Universals
World History
