OLYMPIODORUS THE YOUNGER: "Imagination [phantasía] is a constant impediment to the operations of our intellect.... And so Odysseus needed the moly and straight talk of Hermes to escape the apparition of Kalypso, which obscured his reason as clouds obscure the sun. Not for nothing is she somewhere called "mirage with trailing robes" -- Kalypso was herself a kálymma [a 'covering']. Accordingly, the Kalypso episode was preceded by Odysseus's landing on the island of Kirke, who (as the daughter of the sun) stands for perception.
"Thus does imagination constitute an impediment to our intellect. And when in the grip of a divine visitation we let imagination intrude, the divine energy lapses. For enthusiasm and imagination are directly opposed. And so Epictetus bids us to say within ourselves: 'You are an apparition, and in no way a true appearance' [Encheiridion I.5] -- and [yet] under the influence of imagination the philosophical choir of Stoics understood God to be a corporeal entity. For imagination is what wraps the incorporeal in a body.
"What, then, does [Aristotle] say? 'Without imagination, there is no thought'? But surely, what the soul knows of universals owes nothing to the activity of the imagination."
"How is it that 'We do not think without imagination'? It's that imagination accompanies thought, not as a complement but as a persecutor, the way a storm accompanies the sailor on the sea."