Usage[edit]
The objects or concepts that have intelligibility may be called intelligible. Some possible examples are numbers and the logical law of non-contradiction.
There may be a distinction between everything that is intelligible and everything that is visible, called the intelligible world and the visible world in e.g. the analogy of the divided line as written by Plato.[1]
Plato[edit]
Plato referred to the intelligible realm of mathematics, forms, first principles, logical deduction, and the dialectical method. The intelligible realm of thought thinking about thought does not necessarily require any visual images, sensual impressions, and material causes for the contents of mind.
Plotinus[edit]
According to Plotinus, the power of the Demiurge (the 'craftsman' of the cosmos) is derived from the power of thought. When the demiurge creates, he governs the purely passive nature of matter by imposing a sensible form, which is an image of the intelligible forms contained as thoughts within the mind of the Demiurge, upon the pure passivity of matter. The form establishes its existence in the sensible realm merely through the thought of the Demiurge, which is nous.[3]
Aquinas[edit]
In chapter 81 of the Compendium Theologiae, Saint Thomas Aquinas states that "the higher an intellectual substance is in perfection, the more universal are the intelligible forms it possesses. Of all the intellectual substances, consequently, the human intellect, which we have called possible, has forms of the least universality. This is the reason it receives its intelligible forms from sensible things." He further states that "a form must have some proportion to the potency which receives it. Therefore, since of all intellectual substances man’s possible intellect is found to be the closest to corporeal matter, its intelligible forms must, likewise, be most closely allied to material things.[4]