Cube of Space: Stoic Philosophy: Four Powers of the Hegemonikon

Cube of Psychological Space: Stoic Philosophy: Four Powers of the Hegemonikon

The Stoic philosophers identified the seat of the soul as the Hegemonikon, the central facility which receives and organizes the impressions of phantasia, or imagination, delivered by the senses.

The Hegemonikon has four powers: phantasia, reason, impulse and assent. Phantasia may be either aesthetic (sensory) or mental reproductions of stored past phantasies. Impulse is a desire (an inclination to act) towards a phantasia and assent is the action performed after evaluation of the object of desire.

Imagination won't be fully divorced from sensation until Hume. Yesterday's Imagination and Reason have become today's sensation and perception.

In any case, we find our familiar axes of experience and life, defined by the polarities of sense-perception and future-past. Phantasia and Logos interact to produce inner and outer experience; Impulse is determined by past impressions and Assent determines the course of the future. See Metapsychology of the Cube of Space.

In addition to the eight parts of the soul, the human hêgemonikon itself was characterized by four basic powers: presentation [phantasia], impulse [hormê], assent [sugkatathesis], and reason [logos]. Iamblicus tells us that the eight parts of the soul differ in bodily substrata while the four powers of the hêgemonikon must be individuated by quality in regards to the same. In other words, the four powers of the hêgemonikon are not individually isolated in space; their identity seems to be characterized exclusively by their function.
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The Stoics distinguished presentations drawn directly from the senses [aisthetike phantasiai] and those which are produced by the mind from previously experienced phantasiai. The doctrine of presentation also provided the foundation for a theory of memory and concept formation. Memory was seen to be stored phantasiai. Conceptions [ennoêmata] on the other hand seemed to be collections or patterns of stored phantasiai. The Stoic theory is flexible enough to account for real and fictional (intentional) objects, thereby establishing a plausible theory of imagination. The Stoics distinguished between phantasia, phantaston, phantastikon, and phantasma. The phantaston is the object producing the phantasia. A phantastikon is a phantasia which does not come from a real object, such as those produced by the imagination. Imagination was explained as the manipulation of mental content.

Stoic Philosophy of Mind [Internet Encyclopedia of Philosophy]

hêgemonikon 'commanding faculty' of the soul (psuchê); the centre of consciousness, the seat of all mental states, thought by the Stoics (and other ancients) to be located in the heart. It manifests four mental powers: the capacity to receive impressions, to assent to them, form intentions to act in response to them, and to do these things rationally. The Discourses talk of keeping the prohairesis in the right condition, and also of keeping the hêgemonikon in the right condition, and for Epictetus these notions are essentially interchangeable.