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From Plato to Philo: On the Psychology and Physiology of Prophetic Dreaming

Jason Reddoch

In this presentation, I will provide an analysis of Philo of Alexandria’s reformulation of two of Plato’s comments on divination through dreams (Rep 9.571c-572c, Tim 70d-72c). In the Republic, Plato explains that indulging in the passions and stimulating the irrational part of the soul hinders one’s ability to have prophetic dreams. Plato’s explanation thus makes divination a function of the rational part of the soul and emphasizes an ethical component. In the Timaeus, Plato explains prophetic dreaming as a product of the reflective capacity of the liver, which is situated in the part of the body associated with irrationality. Nowhere in the extant Platonic corpus does Plato reconcile these two explanations or discuss them collectively.

The influence of Plato’s Republic on Philo’s understanding of prophetic dreaming is evident when Philo describes divination through dreams as a process of moral and spiritual purification (e.g. Migr. 184-194). As I have argued previously (“Enigmatic Dreams and Onirocritical Skill,” The Studia Philonica Annual (2013) 25), Philo also organizes his tripartite dream classification according to the basic principle that indulging in the passions makes prophetic dreaming more difficult.

The influence of Plato’s Timaeus on Philo is evident in his treatise De Specialibus Legibus in which he describes the various parts of animals that are appropriate for sacrifice. He pauses to explain the significance of the liver for purifying food and creating blood and in this context also emphasizes the process through which the liver enables prophetic dreaming (Spec. 1.219). In this passage, which is directly modeled on the passage from Plato’s Timaeus, Philo also includes the psychological/ethical component inherited from Plato’s Republic. According to Philo, the liver only reflects prophetic images when the mind is purified: “Whenever the mind has withdrawn from its daily thought and the body is relaxed by sleep and none of the perceptions stand in the way, the mind begins to turn itself about and to gaze purely by itself at its thoughts. Gazing at the liver just as a mirror, it beholds purely each of its thoughts…and being pleased by all the phantasiai, the mind foretells the future through dreams” (Spec. 1.219).

Philo’s ability to combine these psychological and physiological models for prophetic dreams can best be explained by his use of various types of phantasiai, which allow him to describe psychological experience in terms of the presence or absence of sensory information. When Philo describes prophetic dreaming in his treatise on the migration of Abraham, he explains that one is only able to have prophetic visions when one has made sufficient moral progress so that the mind is free from sensory phantasiai (αἱ κατὰ αἰσθήσεις φαντασίαι). Elsewhere Philo explains that only those who are “the friends of the soul” (and not “the friends of the body”) are able to able to perceive God’s true incorporeal essence (φαντασία κατὰ τὸ εἶναι, Deus 55).

Identifying these two types of phantasiai explains how Philo is able to combine his psychological/ethical and physiological explanations inherited from Plato. Indulging in the passions stimulates the irrational part of the soul and makes divination difficult since the prophetic vision is obscured by sensory phantasiai. The purification of the soul, on the other hand, allows the mind to be free from sensory phantasiai and behold a pure prophetic image through the reflective capacity of the liver.

In conclusion, although it is unclear to what extent Philo is original, his synthesis of Platonic influences can be attributed to two developments. His use of phantasia to explain the psychology of divination through dreams is a product of developments in the Stoa, where categories of various kinds of phantasiai were highly developed. The idea that the liver’s reflective function can be understood in terms of moral purification is probably due to advances in post-classical medicine.

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Platonism and the Irrational

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