Medical Compendium: Galen and Hippocrates

...specifically in the imaginations, just as images are seen in mirrors. And just as the light within the eye is not itself seen, but is the cause of seeing, so too is the imaginative spirit phantastikon pneuma original: "πνεῦμα τὸ φανταστικόν." In Neoplatonic thought, this is a "spirit-vehicle" that acts as an intermediary between the immaterial soul and the physical body.. It is not itself perceptible by the senses, but is the cause of the sense-organs, and it is prepared to receive all forms of sensation. Therefore, just as the onslaught of passions disturbs the mind when the images are beastly, irrational, and turbulent, so too does the grace from the gods—which ascends toward the divine—reveal the radiance of the spirit by removing that turbulence.

51 It might perhaps seem redundant to go through the rest of the sense-organs to show that the imaginative spirit is the common sense-organ koinon aistheterion original: "κοινὸν αἰσθητήριον." This is the central faculty that processes and unifies the data from the five individual senses. for them all. This is the primary "body" of the soul—not only the first, but the only one—and it resides within the head as if in a citadel. The other senses are distinct from it and stand apart. Some are external instruments, like porters; others are internal, like those who tend to our feelings; while others are external, like guards. All the senses report back to this common sense-organ, which holds a kind of sovereign authority. Thus, by granting leadership to that which is superior,

nothing should weigh us down, but we should instead steer the ship. For the divine beings of that realm do not lack our help, nor do they suffer along with us. Instead, we see them and the things of this world as they truly are, without the distortion or outrage to which they are subjected here. Even those things which by nature do not accept such "sympathy" original: "συμπάθειαν," here referring to the interconnectedness or shared suffering between the physical and spiritual worlds find it sufficient to be transformed by it.

52 It is not possible to see the vast number of medicines or the riddles given to us by the gods through images unless the spirit is clear. Just as the onslaught of passions disturbs the mind when images are beastly, irrational, and turbulent, so too does the grace from the gods—which ascends toward the divine—reveal the radiance of the spirit by removing that turbulence. Indeed, one could not see the images in a mirror if the mirror itself were shaken; in such a case, the images themselves would be unstable, muddy, and obscure. In the same way, when the imaginative spirit is full of internal noise and instability, it does not receive the divine images, or it receives them only in a faint and confused manner. But if it is calm original: "γαληνιᾷ," a term often used for a calm sea, suggesting a meditative or peaceful state of mind, then the divine images appear clear and vivid. Therefore, such things in our sleep are nothing other than divine visions, which we call dreams original: "ὀνείρους". These are beneficial not only to our bodies but also to our souls. They release the soul from its passions and lead it, pure and holy, up toward the gods. Let this be said as a summary: that the imaginative spirit, as has been stated, is our first and most sovereign sense-organ.

53 It might perhaps seem redundant to enumerate the rest of its uses. However, it may be that this point is not entirely obvious to everyone. The primary and most sovereign points have been stated sufficiently and demonstratively. It is fitting to set a seal upon how each thing is found to be. For every essence—both the primary "body" and everything following it—was created rightly from the principle within it. But everyone makes use of what exists; for in practice, the future is hidden from man. Yet how the whole world fulfills our needs is taken up toward the